A291846 Central terms in irregular triangle A291845.

1, 1, 5, 33, 283, 2995, 37723, 551047, 9157923, 170606547, 3521075919, 79741123539, 1965955092517, 52414187219485, 1502559229282213, 46087421890091145, 1506033038595292467, 52232959640093489043, 1916263566511685329711, 74142047814365044902307, 3017192203838382727894241, 128829022389463544587355721, 5758871157244067281788041809

Offset

0,3

Comments

G.f. of row n in triangle A291845 equals Product_{k=0..n-1} (1 + (2*k+1)*x + x^2), with row sums equal to the odd double factorials A001147.

Links

Paul D. Hanna, Table of n, a(n) for n = 0..300

Formula

a(n) = A291845(n,n).

Prog

(PARI) /* As Central Terms of Triangle A291845 */
{A291845(n, k)=polcoeff(prod(j=0, n-1, 1 + (2*j+1)*x + x^2), k)}
{for(n=0, 25, print1(A291845(n, n), ", "))}

Crossrefs

Cf. A291845, A291847, A291848.

Sequence in context: A120733 A218496 A144792 * A255927 A001828 A084845

Adjacent sequences: A291843 A291844 A291845 * A291847 A291848 A291849

Keyword

nonn

Author

Paul D. Hanna, Sep 03 2017

Status

approved