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 A365969 #24 Sep 24 2023 09:15:58 %S A365969 1,1,1,1,1,1,121,841,3361,10081,25201,3684241,50309281,369738721, %T A365969 1926648361,7980936601,1335634023361,27705746752321,302258931418081, %U A365969 2283161710263841,13419441405835201,2498339829188508481,70152448708746111961,1025314852704395518441 %N A365969 Expansion of e.g.f. exp( Sum_{k>=0} x^(5*k+1) / (5*k+1) ). %F A365969 a(0) = 1; a(n) = (n-1)! * Sum_{k=0..floor((n-1)/5)} a(n-5*k-1)/(n-5*k-1)!. %F A365969 a(0) = a(1) = ... = a(4) = 1; a(n) = a(n-1) + 120 * binomial(n-1,5) * a(n-5). %o A365969 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=0, N\5, x^(5*k+1)/(5*k+1))))) %Y A365969 Cf. A000246, A193437, A193438. %Y A365969 Cf. A333882, A365977. %K A365969 nonn %O A365969 0,7 %A A365969 _Seiichi Manyama_, Sep 23 2023