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A328063
Amicable pairs with the property that the number of divisors of the smaller member is greater than the number of divisors of the larger member.
8
220, 284, 6232, 6368, 12285, 14595, 17296, 18416, 63020, 76084, 69615, 87633, 79750, 88730, 100485, 124155, 122265, 139815, 141664, 153176, 142310, 168730, 185368, 203432, 280540, 365084, 308620, 389924, 319550, 430402, 356408, 399592, 600392, 669688, 609928, 686072, 624184, 691256
OFFSET
1,1
COMMENTS
Amicable pairs(x,y) such that d(x) > d(y), where d(n) is the number of divisors of n.
LINKS
EXAMPLE
Consider the amicable pair [220, 284]. The smaller member has 12 divisors, they are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220. The larger member has 6 divisors, they are 1, 2, 4, 71, 142, 284. The number of divisors of 220 is greater than the number of divisors of 284, so the amicable pair [220, 284] is in the sequence.
MATHEMATICA
seq = {}; s[n_] := DivisorSigma[1, n] - n; Do[m = s[n]; If[m > n && s[m] == n && DivisorSigma[0, n] > DivisorSigma[0, m], seq = Join[seq, {n, m}]], {n, 1, 7*10^5}]; seq (* Amiram Eldar, Oct 11 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Oct 03 2019
STATUS
approved