This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A182227 #19 Apr 06 2024 07:54:06 %S A182227 6,3,1,24,27,55,20,19,76,21,14,108,23,3,123,12,66,140,3,144,156,22,12, %T A182227 1,172,52,12,240,123,204,12,126,259,147,236,138,66,312,12,42,546,12, %U A182227 316,7,171,165,198,44,366,384,174,12,112,218,117,744,12,476,12,198 %N A182227 Sum of divisors of the abundant number m = A005101(n) which are smaller than its abundance A033880(m). %C A182227 Motivated by A100696. See also A182225 and A182226. %H A182227 Amiram Eldar, <a href="/A182227/b182227.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from M. F. Hasler) %t A182227 f[n_] := If[(ab = DivisorSigma[1, n] - 2*n) > 0 ,DivisorSum[n, # &, # < ab &],Nothing]; Array[f, 300] (* _Amiram Eldar_, Apr 06 2024 *) %o A182227 (PARI) f(n)=my(A=sigma(n)-2*n,s);fordiv(n,d,(d<A && s+=d) || break);s %o A182227 for(n=1,500,sigma(n)>2*n & print1(f(n)",")) %Y A182227 Cf. A005101, A033880, A100696, A182225, A182226. %K A182227 nonn %O A182227 1,1 %A A182227 _M. F. Hasler_, Apr 19 2012