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, 29961, 545, 1

Offset

0,5

Links

Table of n, a(n) for n=0..54.

Formula

T(n,k) = Sum_{j=0..n} C(2(n-k), j) * C(2k, j) * 2^j if 0<=k<=n otherwise 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

Row sums are A108475.

Diagonal sums are A108478.

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