A205550 Symmetric matrix by antidiagonals: C(max(g(i),g(j)),min(g(i),g(j))), where g(k)=2k-1.
1, 3, 3, 5, 1, 5, 7, 10, 10, 7, 9, 35, 1, 35, 9, 11, 84, 21, 21, 84, 11, 13, 165, 126, 1, 126, 165, 13, 15, 286, 462, 36, 36, 462, 286, 15, 17, 455, 1287, 330, 1, 330, 1287, 455, 17, 19, 680, 3003, 1716, 55, 55, 1716, 3003, 680, 19, 21, 969, 6188, 6435, 715
Offset: 1
Examples
Northwest corner: 1....3....5....7....9....11 3....1....10...35...84...165 5....10...1....21...126..462 7....35...21...1....36...330
Crossrefs
Cf. A205456.
Programs
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Mathematica
g[k_] := 2 k - 1; f[i_, j_] := Binomial[Max[g[i], g[j]], Min[g[i], g[j]]] TableForm[Table[f[i, j], {i, 1, 10}, {j, 1, 10}]] Flatten[Table[f[i, n + 1 - i], {n, 1, 14}, {i, 1, n}]]