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 A352304 #19 Aug 21 2024 11:23:39 %S A352304 1,-1,1,-1,25,-241,1441,-6721,67201,-1185409,16652161,-180639361, %T A352304 2098673281,-37526586241,785718950017,-14516030954881,247504017895681, %U A352304 -4832929862019841,116556246644716801,-2930255897793414913,69746855593499124481,-1673960044278244020481 %N A352304 Expansion of e.g.f. 1/(exp(x) - x^4). %F A352304 a(n) = n * (n-1) * (n-2) * (n-3) * a(n-4) - Sum_{k=1..n} binomial(n,k) * a(n-k) for n > 3. %F A352304 a(n) ~ n! * (-1)^n / ((1 + LambertW(1/4)) * 2^(2*n + 10) * LambertW(1/4)^(n+4)). - _Vaclav Kotesovec_, Mar 12 2022 %F A352304 a(n) = n! * Sum_{k=0..floor(n/4)} (-k-1)^(n-4*k)/(n-4*k)!. - _Seiichi Manyama_, Aug 21 2024 %t A352304 m = 21; Range[0, m]! * CoefficientList[Series[1/(Exp[x] - x^4), {x, 0, m}], x] (* _Amiram Eldar_, Mar 12 2022 *) %o A352304 (PARI) my(N=40, x='x+O('x^N)); Vec(serlaplace(1/(exp(x)-x^4))) %o A352304 (PARI) b(n, m) = if(n==0, 1, sum(k=1, n, (-1+(k==m)*m!)*binomial(n, k)*b(n-k, m))); %o A352304 a(n) = b(n, 4); %Y A352304 Cf. A089148, A352302, A352303. %Y A352304 Cf. A352300, A352311. %K A352304 sign %O A352304 0,5 %A A352304 _Seiichi Manyama_, Mar 11 2022