Sha256: 03d0b55037040fcf0803de3ee84b5a8f43ba9aa3a2ab302f7ca2363e5d09c859
Contents?: true
Size: 515 Bytes
Versions: 31
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Stored size: 515 Bytes
Contents
# coding: utf-8
class Integer
# Implementation of Stewart, B. M. (1954), "Sums of distinct divisors",
# American Journal of Mathematics 76: 779–785, doi:10.2307/2372651,
# MR0064800
def practical?
sum = 1
k = 2
n = self
while (n >= k)
s = 1
u = 0
while (n % k == 0)
n = n/k
s = s * k + 1
u += 1
end
unless (u == 0)
return false if (k > sum + 1)
sum *= s
end
k += (k == 2) ? 1 : 2
end
true
end
end
Version data entries
31 entries across 31 versions & 1 rubygems