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 A210950 #27 Oct 22 2023 17:05:38 %S A210950 1,1,2,1,2,3,1,2,4,5,1,2,4,6,7,1,2,4,7,10,11,1,2,4,7,11,14,15,1,2,4,7, %T A210950 12,17,21,22,1,2,4,7,12,18,25,29,30,1,2,4,7,12,19,28,36,41,42,1,2,4,7, %U A210950 12,19,29,40,50,55,56,1,2,4,7,12,19,30,43 %N A210950 Triangle read by rows: T(n,k) = number of parts in the k-th column of the partitions of n but with the partitions aligned to the right margin. %C A210950 Index of the first partition of n that has k parts, when the partitions of n are listed in reverse lexicographic order, as in Mathematica's IntegerPartitions[n]. - _Clark Kimberling_, Oct 16 2023 %F A210950 T(n,k) = Sum_{j=1..n} A210951(j,k). %e A210950 For n = 6 the partitions of 6 aligned to the right margin look like this: %e A210950 . %e A210950 . 6 %e A210950 . 3 + 3 %e A210950 . 4 + 2 %e A210950 . 2 + 2 + 2 %e A210950 . 5 + 1 %e A210950 . 3 + 2 + 1 %e A210950 . 4 + 1 + 1 %e A210950 . 2 + 2 + 1 + 1 %e A210950 . 3 + 1 + 1 + 1 %e A210950 . 2 + 1 + 1 + 1 + 1 %e A210950 . 1 + 1 + 1 + 1 + 1 + 1 %e A210950 . %e A210950 The number of parts in columns 1-6 are %e A210950 . 1, 2, 4, 7, 10, 11, the same as the 6th row of triangle. %e A210950 Triangle begins: %e A210950 1; %e A210950 1, 2; %e A210950 1, 2, 3; %e A210950 1, 2, 4, 5; %e A210950 1, 2, 4, 6, 7; %e A210950 1, 2, 4, 7, 10, 11; %e A210950 1, 2, 4, 7, 11, 14, 15; %e A210950 1, 2, 4, 7, 12, 17, 21, 22; %e A210950 1, 2, 4, 7, 12, 18, 25, 29, 30; %e A210950 1, 2, 4, 7, 12, 19, 28, 36, 41, 42; %e A210950 1, 2, 4, 7, 12, 19, 29, 40, 50, 55, 56; %e A210950 1, 2, 4, 7, 12, 19, 30, 43, 58, 70, 76, 77; %t A210950 m[n_, k_] := Length[IntegerPartitions[n][[k]]]; c[n_] := PartitionsP[n]; %t A210950 t[n_, h_] := Select[Range[c[n]], m[n, #] == h &, 1]; %t A210950 Column[Table[t[n, h], {n, 1, 20}, {h, 1, n}]] %t A210950 (* _Clark Kimberling_, Oct 16 2023 *) %Y A210950 Mirror of A058399. Row sums give A006128. Right border gives A000041, n >= 1. Rows converge to A000070. %Y A210950 Cf. A135010, A194714, A210945, A210951, A210952, A210953, A210970. %K A210950 nonn,tabl %O A210950 1,3 %A A210950 _Omar E. Pol_, Apr 22 2012