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 A231711 #16 Nov 16 2013 10:20:29 %S A231711 3,4,5,7,8,9,10,11,13,14,15,16,17,19,21,22,23,25,26,27,28,29,31,32,33, %T A231711 34,35,37,38,39,40,41,43,44,45,46,47,49,50,51,52,53,55,56,57,58,59,61, %U A231711 62,63,64,65,66,67,68,69,70,71,73,74,75,76,77,78,79,81,82 %N A231711 Numbers n such that n > sigma(n) - sigma(n-1). %C A231711 Numbers n such that antisigma(n) > antisigma(n-1), where antisigma(n) = A024816(n) = the sum of the non-divisors of n that are between 1 and n. %C A231711 Numbers n such that A163553(n-1) > 0. %C A231711 Numbers n such that antisigma(n) < antisigma(n-1) = A231547. %C A231711 Numbers n such that antisigma(n) = antisigma(n-1) = A231545. %C A231711 Complement of union of A231547, A231545 and number 1. %H A231711 Jaroslav Krizek, <a href="/A231711/b231711.txt">Table of n, a(n) for n = 1..1000</a> %e A231711 10 is in sequence because antisigma(10) = 37 > antisigma(9) = 32. %p A231711 with(numtheory); A231711:=n->`if`(sigma(n)-sigma(n-1)<n,n,NULL); seq(A231711(n), n=1..100); # _Wesley Ivan Hurt_, Nov 14 2013 %o A231711 (PARI) isok(n) = n > sigma(n) - sigma(n-1); \\ _Michel Marcus_, Nov 14 2013 %Y A231711 Cf. A231545, A231546, A231547, A231548, A024816, A163553. %K A231711 nonn %O A231711 1,1 %A A231711 _Jaroslav Krizek_, Nov 12 2013