A123934 Triangle T(n,k), 1<=k<=n :forms the odd-indexed trinomial coefficients (A027907).

1, 2, 2, 3, 7, 3, 4, 16, 16, 4, 5, 30, 51, 30, 5, 6, 50, 126, 126, 50, 6, 7, 77, 266, 393, 266, 77, 7

Offset

1,2

Links

Table of n, a(n) for n=1..28.

Formula

Sum_{k, 1<=k<=n}T(n,k)=A003462(n)=(3^n-1)/2.

Example

Triangle begins:
1;
2, 2;
3, 7, 3;
4, 16, 16, 4;
5, 30, 51, 30, 5;
6, 50, 126, 126, 50, 6;
7, 77, 266, 393, 266, 77, 7;

Crossrefs

Cf. A056241.

Sequence in context: A183442 A296019 A134232 * A363365 A208151 A203362

Adjacent sequences: A123931 A123932 A123933 * A123935 A123936 A123937

Keyword

nonn,tabl

Author

Philippe Deléham, Oct 30 2006

Status

approved