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 A328064 Amicable pairs with the property that both members have the same number of divisors. 6
 1184, 1210, 2620, 2924, 5020, 5564, 10744, 10856, 66928, 66992, 67095, 71145, 122368, 123152, 171856, 176336, 176272, 180848, 196724, 202444, 437456, 455344, 503056, 514736, 522405, 525915, 1077890, 1099390, 1154450, 1189150, 1280565, 1340235, 1358595, 1486845, 1392368, 1464592, 2082464, 2090656 (list; graph; refs; listen; history; text; internal format)
 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 Subsequence of A259180. Cf. A000005, A002025, A002046, A328009, A328043, A328063, A328065, A328255. Sequence in context: A210847 A320716 A269017 * A280516 A205994 A345540 Adjacent sequences:  A328061 A328062 A328063 * A328065 A328066 A328067 KEYWORD nonn AUTHOR Omar E. Pol, Oct 03 2019 STATUS approved

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Last modified November 29 01:05 EST 2021. Contains 349415 sequences. (Running on oeis4.)