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 A227983 #7 Jul 25 2021 11:17:59 %S A227983 4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,24,25,26,27,28,29, %T A227983 30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,48,49,50,51,52,53, %U A227983 54,55,56,57,58,60,61,62,63,64,65,66,67,68,69,70,71,72,73 %N A227983 Numbers n such that sigma(n+1) - sigma(n-1) < sigma(n); where sigma(n) = A000203(n) = sum of the divisors of n. %C A227983 See A076530 - numbers n such that sigma(n+1) - sigma(n-1) = sigma(n). %C A227983 Complement of union of A076530, A227982 and number 1. %H A227983 Jaroslav Krizek, <a href="/A227983/b227983.txt">Table of n, a(n) for n = 1..2000</a> %e A227983 Number 60 is in the sequence because sigma(61) - sigma(59) = 62 - 60 = 2 < sigma(60) = 168. %t A227983 Flatten[Position[Partition[DivisorSigma[1,Range[100]],3,1],_?(#[[3]]- #[[1]]< #[[2]]&),1,Heads->False]]+1 (* _Harvey P. Dale_, Jul 25 2021 *) %Y A227983 Cf. A076530, A000203, A227982. %K A227983 nonn %O A227983 1,1 %A A227983 _Jaroslav Krizek_, Aug 08 2013