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 A321921 #4 Nov 23 2018 07:58:56 %S A321921 1,0,1,1,1,0,0,1,0,1,1,1,2,1,0,0,0,0,1,0,1,0,1,1,0,0,0,1,1,0,1,1,2,1, %T A321921 1,2,3,3,1,0,0,0,0,0,0,1,0,0,0,0,0,1,1,0,0,0,1,0,1,1,0,0,1,2,1,2,1,0, %U A321921 0,0,1,1,2,1,0,1,2,3,3,3,1,1,4,5,5,6,4 %N A321921 Tetrangle where T(n,H(u),H(v)) is the coefficient of s(v) in e(u), where u and v are integer partitions of n, H is Heinz number, s is Schur functions, and e is elementary symmetric functions. %C A321921 The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k). %H A321921 Wikipedia, <a href="https://en.wikipedia.org/wiki/Symmetric_polynomial">Symmetric polynomial</a> %e A321921 Tetrangle begins (zeroes not shown): %e A321921 (1): 1 %e A321921 . %e A321921 (2): 1 %e A321921 (11): 1 1 %e A321921 . %e A321921 (3): 1 %e A321921 (21): 1 1 %e A321921 (111): 1 2 1 %e A321921 . %e A321921 (4): 1 %e A321921 (22): 1 1 1 %e A321921 (31): 1 1 %e A321921 (211): 1 1 2 1 %e A321921 (1111): 1 2 3 3 1 %e A321921 . %e A321921 (5): 1 %e A321921 (41): 1 1 %e A321921 (32): 1 1 1 %e A321921 (221): 1 2 1 2 1 %e A321921 (311): 1 1 2 1 %e A321921 (2111): 1 2 3 3 3 1 %e A321921 (11111): 1 4 5 5 6 4 1 %e A321921 For example, row 14 gives: e(32) = s(221) + s(2111) + s(11111). %Y A321921 This is a regrouping of the triangle A321756. %Y A321921 Cf. A005651, A008480, A056239, A124794, A124795, A153452, A215366, A296188, A300121, A319191, A319193, A321912-A321935. %K A321921 nonn,tabf %O A321921 1,13 %A A321921 _Gus Wiseman_, Nov 22 2018