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A205548 Symmetric matrix by antidiagonals:  C(max(i+1,j+1),min(i+1,j+1)), i>=1, j>=1. 2
1, 3, 3, 6, 1, 6, 10, 4, 4, 10, 15, 10, 1, 10, 15, 21, 20, 5, 5, 20, 21, 28, 35, 15, 1, 15, 35, 28, 36, 56, 35, 6, 6, 35, 56, 36, 45, 84, 70, 21, 1, 21, 70, 84, 45, 55, 120, 126, 56, 7, 7, 56, 126, 120, 55, 66, 165, 210, 126, 28, 1, 28, 126, 210, 165, 66, 78, 220 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..68.

EXAMPLE

Northwest corner:

1....3....6....10...15

3....1....4....10...20

6....4....1....5....15

10...10...5....1....6

15...20...15...6....1

MATHEMATICA

g[k_] := 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}]]

CROSSREFS

Cf. A205456.

Sequence in context: A189915 A085572 A342512 * A010609 A066519 A236258

Adjacent sequences:  A205545 A205546 A205547 * A205549 A205550 A205551

KEYWORD

nonn,tabl

AUTHOR

Clark Kimberling, Jan 28 2012

STATUS

approved

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Last modified October 21 02:29 EDT 2021. Contains 348141 sequences. (Running on oeis4.)