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 A061469 GCD of the amicable pairs: a(n) = gcd(A002025(n), A002046(n)). 5
 4, 2, 4, 4, 8, 8, 105, 16, 92, 16, 135, 819, 10, 45, 585, 16, 8, 10, 16, 16, 8, 44, 4, 4, 14, 8, 16, 98, 16, 585, 8, 8, 8, 8, 8, 4, 8, 105, 16, 8, 135, 8, 10, 50, 10, 5733, 8, 585, 10, 855, 16, 10, 4, 10, 10, 585, 32, 10, 8, 16, 14, 8, 16, 4, 8, 310, 8, 16, 8, 10, 50, 855, 14, 8, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The pairs are ordered by the smaller number. - David Wasserman, Jun 18 2002 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from T. D. Noe) Eric Weisstein's World of Mathematics, Amicable Pair. EXAMPLE a(1) = gcd(220, 284) = 4; a(2) = gcd(1184, 1210) = 2. MATHEMATICA With[{s = PositionIndex@ Array[DivisorSigma[1, #] &, 10^6]}, Flatten@ Map[GCD @@ # &, Apply[Join, Map[Function[n, Select[Subsets[Lookup[s, n], {2}], Total@ # == n &]], Sort@ Select[Keys@ s, Length@ Lookup[s, #] > 1 &]]]]] (* Michael De Vlieger, Oct 22 2017 *) CROSSREFS Cf. A002025, A002046, A259180 (amicable pairs). Sequence in context: A057697 A019921 A204617 * A222641 A258852 A021706 Adjacent sequences: A061466 A061467 A061468 * A061470 A061471 A061472 KEYWORD nonn AUTHOR Jason Earls, Jun 11 2001 EXTENSIONS More terms from David Wasserman, Jun 18 2002 a(22) corrected by T. D. Noe, Aug 15 2010 STATUS approved

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Last modified March 28 03:48 EDT 2023. Contains 361577 sequences. (Running on oeis4.)