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yanjunk
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Partial answer:

Numbers with at least 12 divisors, andthat don't divide the product of their first six factors, nor first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460

Code:

from functools import reduce
import operator

def factors(n):    
    return sorted(reduce(list.__add__, 
                ([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0)))
def prod(a, i):
    return reduce(operator.mul, a[0:i], 1)

thing = [factors(i) for i in range(2, 5000)]
newset = set()
for a in thing:
    if prod(a, max(5, len(a) // 2 - 1)) % a[-1] != 0:
        newset.add(a[-1])

In particular, if you only consider the first 6 divisors, the set returned seems to be a superset of the list in the question. Of particular interest is the counterexample 294, which has 12 divisors and like 84 is divisible by the first 6 but not the first 5.

The code is the above but replacing the max(5, ...) with 5.

Partial answer:

Numbers with at least 12 divisors, and don't divide the product of their first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460

In particular, if you only consider the first 6 divisors, the set returned seems to be a superset of the list in the question. Of particular interest is the counterexample 294, which has 12 divisors and like 84 is divisible by the first 6 but not the first 5.

Partial answer:

Numbers that don't divide the product of their first six factors, nor first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460

Code:

from functools import reduce
import operator

def factors(n):    
    return sorted(reduce(list.__add__, 
                ([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0)))
def prod(a, i):
    return reduce(operator.mul, a[0:i], 1)

thing = [factors(i) for i in range(2, 5000)]
newset = set()
for a in thing:
    if prod(a, max(5, len(a) // 2 - 1)) % a[-1] != 0:
        newset.add(a[-1])

In particular, if you only consider the first 6 divisors, the set returned seems to be a superset of the list in the question. Of particular interest is the counterexample 294, which has 12 divisors and like 84 is divisible by the first 6 but not the first 5.

The code is the above but replacing the max(5, ...) with 5.

added 263 characters in body
Source Link
yanjunk
  • 111
  • 3

Partial answer:

Numbers with at least 12 divisors, and don't divide the product of their first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460

In particular, if you only consider the first 6 divisors, the set returned seems to be a superset of the list in the question. Of particular interest is the counterexample 294, which has 12 divisors and like 84 is divisible by the first 6 but not the first 5.

Partial answer:

Numbers with at least 12 divisors, and don't divide the product of their first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460

Partial answer:

Numbers with at least 12 divisors, and don't divide the product of their first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460

In particular, if you only consider the first 6 divisors, the set returned seems to be a superset of the list in the question. Of particular interest is the counterexample 294, which has 12 divisors and like 84 is divisible by the first 6 but not the first 5.

Source Link
yanjunk
  • 111
  • 3

Partial answer:

Numbers with at least 12 divisors, and don't divide the product of their first half of factors (minus one) is pretty close. For reference, the sequence is:

84, 96, 108, 132, 150, 156, 198, 200, 204, 220, 228, 234, 260, 272, 276, 294, 304, 306, 312, 340, 342, 348, 368, 372, 380, 392, 408, 414, 444, 456, 460