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A054572 Larger members of g-reduced amicable pairs a < b such that sigma(a) = sigma(b) = a + b + gcd(a,b). 1

%I #17 May 20 2019 22:49:04

%S 182,184,435,435,801,885,1012,1155,1162,1336,1365,1534,1648,1743,1989,

%T 2295,2318,4527,4917,4935,5229,5428,5974,6128,7155,7582,7708,8733,

%U 9429,11115,11637,13635,14378,15128,15796,16252,17098,17535,18124,20306,21267,22869

%N Larger members of g-reduced amicable pairs a < b such that sigma(a) = sigma(b) = a + b + gcd(a,b).

%C The lesser counterparts are in A054573.

%C 435 appears twice since it has 2 lesser counterparts, 270 and 280. - _Amiram Eldar_, Jan 19 2019

%e 182 is in the sequence since it is the larger member of the pair (140, 182), and sigma(140) = sigma(182) = 336 = 140 + 182 + gcd(140, 182).

%t seq={}; Do[s1 = DivisorSigma[1, n]; Do[s2 = DivisorSigma[1, m]; If[s2 == s1 && s2 == n + m + GCD[n, m], AppendTo[seq, n]], {m, 1, n-1}], {n, 1, 1000}]; seq (* _Amiram Eldar_, Jan 19 2019 *)

%Y Cf. A000203, A002046, A005820 (perfect numbers analog), A054573.

%K nonn

%O 1,1

%A _Yasutoshi Kohmoto_

%E Corrected and extended by _R. J. Mathar_, Oct 19 2006

%E Name corrected and data corrected and extended by _Amiram Eldar_, Jan 19 2019

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Last modified April 24 00:30 EDT 2024. Contains 371917 sequences. (Running on oeis4.)