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 A339034 #16 Feb 01 2024 01:55:15 %S A339034 1,1,4,11,35,147,805,5399,42273,375787,3728261,40788255,487539769, %T A339034 6319430483,88272658797,1321745733511,21117967813025,358591883025339, %U A339034 6448525343069653,122424951294889967,2446864618294774281,51354975368171586595,1129258990476358286909 %N A339034 Row sums of A339033. %H A339034 Paolo Xausa, <a href="/A339034/b339034.txt">Table of n, a(n) for n = 0..440</a> %F A339034 a(n) = n! - (n - 1)! + Sum_{k=1..n} (n + 1 - k)*(k - 1)! for n > 0. %t A339034 A339034[n_] := If[n == 0, 1, n! + Sum[(n+1-k)*(k-1)!, {k, n-1}]]; %t A339034 Array[A339034, 25, 0] (* _Paolo Xausa_, Jan 31 2024 *) %o A339034 (SageMath) %o A339034 def A339034(n): %o A339034 if n == 0: return 1 %o A339034 d = factorial(n) - factorial(n - 1) %o A339034 return add((n + 1 - k)*factorial(k - 1) for k in (1..n)) + d %o A339034 print([A339034(n) for n in (0..22)]) %o A339034 (PARI) a(n) = if (n==0, 1, n! - (n-1)! + sum(k=1, n, (n+1-k)*(k-1)!)); \\ _Michel Marcus_, Dec 02 2020 %Y A339034 Cf. A339033. %K A339034 nonn %O A339034 0,3 %A A339034 _Peter Luschny_, Nov 20 2020