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 A076528 #17 May 23 2025 15:29:38 %S A076528 955,1301,11143,38215,89485,152155,167785,254137,303281,473317,574717, %T A076528 813921,918081,1307023,2008361,3676243,9878245,10368513,12548755, %U A076528 19411481,22493263,42413485,77766487,81513817,157874001,240828973 %N A076528 Numbers n such that sigma(n) = sigma(n-1) - sigma(n-2). %H A076528 Giovanni Resta, <a href="/A076528/b076528.txt">Table of n, a(n) for n = 1..170</a> (terms < 10^13) %F A076528 a(n) = A073500(n)+1 - _Alex Ratushnyak_, Jul 06 2013. %e A076528 sigma(955) = 1152 sigma(954) = 2106 sigma(953) = 954 and 1152 = 2106 - 954; hence 955 is a term of the sequence. %t A076528 Select[Range[3, 10^5], DivisorSigma[1, # ] == DivisorSigma[1, # - 1] - DivisorSigma[1, # - 2] &] %t A076528 Flatten[Position[Partition[DivisorSigma[1,Range[37*10^5]],3,1],_?(#[[3]]==#[[2]]-#[[1]]&),1,Heads->False]]+2 (* The program generates the first 16 terms of the sequence. *) (* _Harvey P. Dale_, May 23 2025 *) %Y A076528 Cf. A000203, A073500. %K A076528 nonn %O A076528 1,1 %A A076528 _Joseph L. Pe_, Oct 18 2002 %E A076528 a(6)-a(26) from _Donovan Johnson_, Feb 01 2009