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 A034697 #5 Jul 08 2025 21:27:20 %S A034697 1,1,2,3,2,3,4,5,2,3,4,5,4,5,6,5,2,3,4,5,4,7,6,7,4,3,6,3,6,7,6,7,2,7, %T A034697 4,7,4,5,6,7,4,5,8,9,6,5,8,9,4,5,4,5,6,7,4,7,6,7,8,9,6,7,8,7,2,7,8,9, %U A034697 4,9,8,9,4,5,6,5,6,9,8,9 %N A034697 a(1)=1, a(n)= 1 + Sum a(p), p prime, p | n-1. %D A034697 Suggested by Bach and Shallit, Algorithmic Number Theory, I, p. 270. %Y A034697 Cf. A037202. %K A034697 nonn %O A034697 1,3 %A A034697 _N. J. A. Sloane_