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 A356402 #10 Aug 05 2022 10:48:20 %S A356402 1,1,3,16,86,626,5267,50793,543279,6544805,86503762,1242678141, %T A356402 19259416827,321457169151,5736414618209,108931865485750, %U A356402 2191495621647324,46604972526167314,1043844453093239627,24555321244430950299,605239630722584461955,15600222966916650541099 %N A356402 Expansion of e.g.f. ( Product_{k>0} (1+x^k)^(1/k!) )^(1/(1-x)). %F A356402 a(0) = 1; a(n) = Sum_{k=1..n} A356401(k) * binomial(n-1,k-1) * a(n-k). %o A356402 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(prod(k=1, N, (1+x^k)^(1/k!))^(1/(1-x)))) %o A356402 (PARI) a356401(n) = n!*sum(k=1, n, sumdiv(k, d, (-1)^(d+1)/(d*(k/d)!))); %o A356402 a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, a356401(j)*binomial(i-1, j-1)*v[i-j+1])); v; %Y A356402 Cf. A298906, A356025, A356392, A356401. %K A356402 nonn %O A356402 0,3 %A A356402 _Seiichi Manyama_, Aug 05 2022