A108477 A symmetric number triangle based on 2^n.

1, 1, 1, 1, 13, 1, 1, 41, 41, 1, 1, 85, 321, 85, 1, 1, 145, 1289, 1289, 145, 1, 1, 221, 3649, 8989, 3649, 221, 1, 1, 313, 8361, 40081, 40081, 8361, 313, 1, 1, 421, 16641, 134245, 265729, 134245, 16641, 421, 1, 1, 545, 29961, 369305, 1256465, 1256465, 369305

Offset

0,5

Comments

Row sums are A108475. Diagonal sums are A108478.

Links

Table of n, a(n) for n=0..51.

Formula

Number triangle T(n, k)=if(k<=n, sum{j=0..n, C(2(n-k), j)C(2k, j)2^j}, 0)

Example

Rows begin
1;
1,1;
1,13,1;
1,41,41,1;
1,85,321,85,1;
1,145,1289,1289,145,1;

Crossrefs

Sequence in context: A010225 A060361 A141596 * A176204 A176492 A174731

Adjacent sequences: A108474 A108475 A108476 * A108478 A108479 A108480

Keyword

easy,nonn,tabl

Author

Paul Barry, Jun 04 2005

Status

approved