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 A361616 #23 Mar 26 2023 11:09:39 %S A361616 1,1,1,1,2,1,1,3,7,1,1,4,15,34,1,1,5,25,103,209,1,1,6,37,214,885,1546, %T A361616 1,1,7,51,373,2293,9051,13327,1,1,8,67,586,4721,29176,106843,130922,1, %U A361616 1,9,85,859,8481,70981,427189,1425495,1441729,1 %N A361616 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..n} binomial(n+(k-1)*(j+1),n-j)/j!. %F A361616 E.g.f. of column k: exp( x/(1-x)^k ) / (1-x)^k. %F A361616 T(n,k) = Sum_{j=0..n} (n+(k-1)*(j+1))!/(k*j+k-1)! * binomial(n,j) for k > 0. %e A361616 Square array begins: %e A361616 1, 1, 1, 1, 1, 1, ... %e A361616 1, 2, 3, 4, 5, 6, ... %e A361616 1, 7, 15, 25, 37, 51, ... %e A361616 1, 34, 103, 214, 373, 586, ... %e A361616 1, 209, 885, 2293, 4721, 8481, ... %e A361616 1, 1546 ,9051, 29176, 70981, 146046, ... %o A361616 (PARI) T(n,k) = n! * sum(j=0, n, binomial(n+(k-1)*(j+1), n-j)/j!); %Y A361616 Columns k=0..3 give A000012, A002720, A343884, A351767. %Y A361616 Main diagonal gives A361617. %Y A361616 Cf. A293985, A361600. %K A361616 nonn,tabl %O A361616 0,5 %A A361616 _Seiichi Manyama_, Mar 18 2023