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
Amiram Eldar, Table of n, a(n) for n = 1..20000
EXAMPLE
Consider the amicable pair [1184, 1210]. The smaller member has 12 divisors, they are 1, 2, 4, 8, 16, 32, 37, 74, 148, 296, 592, 1184. The larger member has 12 divisors, they are 1, 2, 5, 10, 11, 22, 55, 110, 121, 242, 605, 1210. The number of divisors of 1184 is equal to the number of divisors of 1210, so the amicable pair [1184, 1210] 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, 10^6}]; seq (* Amiram Eldar, Oct 11 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Oct 03 2019
STATUS
approved