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 A255009 #10 Jan 05 2024 12:29:10
%S A255009 1,1,1,1,1,2,1,1,4,6,1,1,4,36,12,1,1,8,108,144,60,1,1,4,216,864,3600,
%T A255009 20,1,1,8,324,3456,108000,3600,140,1,1,8,1944,10368,2160000,12000,
%U A255009 176400,280,1,1,16,1944,124416,32400000,2160000,4116000
%N A255009 Array T(n,k) read by ascending antidiagonals, where T(n,k) is the denominator of polygamma(n, 1) - polygamma(n, k).
%C A255009 See A255008.
%t A255009 T[n_, k_] := (-1)^(n+1)*n!*HarmonicNumber[k-1, n+1] // Denominator; Table[T[n-k, k], {n, 0, 10}, {k, 1, n}] // Flatten
%Y A255009 Cf. A001008, A002805, A007406, A007407, A255006, A255007, A255008 (numerators).
%K A255009 nonn,frac,tabl,easy
%O A255009 0,6
%A A255009 _Jean-François Alcover_, Feb 12 2015