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 A113651 #7 Feb 16 2025 08:32:59 %S A113651 2,7,0,47,2,167,287,2,527,2,2,1367,2,1847,2207,2807,2,2,4487,2,5327,2, %T A113651 6887,2,9407,2,10607,11447,2,12767,16127,2,18767,2,2,2,24647,26567, %U A113651 27887,29927,2,2,2,37247,38807,2,2,49727,51527,2,54287,2,2,2,66047 %N A113651 2*JacobiSymbol(p,5) mod p^2 for p=prime(n). %H A113651 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Wall-Sun-SunPrime.html">Wall-Sun-Sun Prime</a> %o A113651 (PARI) a(n) = my(p=prime(n)); 2*kronecker(p, 5) % p^2; \\ _Michel Marcus_, Aug 03 2014 %K A113651 nonn %O A113651 1,1 %A A113651 _Eric W. Weisstein_, Nov 03 2005