A112906 A skew generalized Pascal triangle.

1, 0, 3, 0, 1, 10, 0, 0, 6, 33, 0, 0, 1, 29, 109, 0, 0, 0, 9, 126, 360, 0, 0, 0, 1, 57, 516, 1189, 0, 0, 0, 0, 12, 306, 2034, 3927, 0, 0, 0, 0, 1, 94, 1491, 7807, 12970, 0, 0, 0, 0, 0, 15, 600, 6813, 29382, 42837, 0, 0, 0, 0, 0, 1, 140, 3385, 29737, 108923, 141481, 0, 0, 0, 0, 0, 0

Offset

0,3

Comments

Main diagonal is A006190. Row sums are A007482. Column sums are A001076(n+1). Compare with [0,1/3,-1/3,0,0,..] DELTA [3,1/3,-1/3,0,0,...] where DELTA is the operator defined in A084938. A skewed version of the Riordan array (1/(1-3x-x^2),x/(1-3x-x^2)).

Links

Table of n, a(n) for n=0..71.

Formula

G.f.: 1/(1-3xy(1+x/3)-x^2*y^2); T(n, k)=sum{j=0..floor((2k-n)/2), C(k-j, n-k)C(2k-n, j)3^(2k-2j-n)}; T(n, k) = 3*T(n-1, k-1)+T(n-2, k-1)+T(n-2, k-2).

Example

Triangle begins
1;
0, 3;
0, 1, 10;
0, 0, 6, 33;
0, 0, 1, 29, 109;
0, 0, 0, 9, 126, 360,
0, 0, 0, 1, 57, 516, 1189;
0, 0, 0, 0, 12, 306, 2034, 3927;
0, 0, 0, 0, 1, 94, 1491, 7809, 12970;

Crossrefs

Cf. A112899.

Sequence in context: A211608 A058175 A353010 * A137375 A380128 A376788

Adjacent sequences: A112903 A112904 A112905 * A112907 A112908 A112909

Keyword

easy,nonn,tabl

Author

Paul Barry, Oct 05 2005

Status

approved