A205549 Symmetric matrix by antidiagonals: C(max(i+2,j+2),min(i+2,j+2)), i>=1, j>=1.

1, 4, 4, 10, 1, 10, 20, 5, 5, 20, 35, 15, 1, 15, 35, 56, 35, 6, 6, 35, 56, 84, 70, 21, 1, 21, 70, 84, 120, 126, 56, 7, 7, 56, 126, 120, 165, 210, 126, 28, 1, 28, 126, 210, 165, 220, 330, 252, 84, 8, 8, 84, 252, 330, 220, 286, 495, 462, 210, 36, 1, 36, 210, 462

Offset

1,2

Links

Table of n, a(n) for n=1..64.

Example

Northwest corner:
1....4....10...20...35
4....1....5....15...35
10...5....1....6....21
20...15...6....1....7

Mathematica

g[k_] := k + 2;
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}]]

Crossrefs

Cf. A205456, A205548.

Sequence in context: A202409 A091016 A198025 * A120395 A321078 A160723

Adjacent sequences: A205546 A205547 A205548 * A205550 A205551 A205552

Keyword

nonn,tabl

Author

Clark Kimberling, Jan 28 2012

Status

approved