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 A069926 #21 Aug 30 2018 11:43:15 %S A069926 1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3, %T A069926 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, %U A069926 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3 %N A069926 Number of k, 1<=k<=n, such that k divides sigma(k). %C A069926 a(n) is the number of multiply-perfect numbers (A007691) <= n. - _Robert Israel_, Aug 29 2018 %H A069926 Robert Israel, <a href="/A069926/b069926.txt">Table of n, a(n) for n = 1..10000</a> %F A069926 a(n) = Card(k: 1<=k<=n : sigma(k) == 0 (mod k) ). %o A069926 (PARI) for(n=1,150,print1(sum(i=1,n,if(sigma(i)%(i),0,1)),",")) %Y A069926 Cf. A007691. %K A069926 easy,nonn %O A069926 1,6 %A A069926 _Benoit Cloitre_, May 05 2002