A112294 Diagonal sums of number triangle A112292.

1, 1, 4, 18, 121, 1055, 11376, 145852, 2165689, 36532197, 689873284, 14415662558, 330204013569, 8226714806323, 221470234531456, 6406397898751320, 198160750081637521, 6526636388676159977, 228040136335670652324

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Formula

a(n)=sum{k=0..floor(n/2), (2n-2k-1)!!/(2k-1)!!}; a(n)=sum{k=0..floor(n/2), 2^(n-2k)(n-k-1/2)!/(k-1/2)!}; a(n)=sum{k=0..floor(n/2), (n-k)!C(2n-2k, n-k)2^(2k-n)/(k!C(2k, k))}; a(n)=sum{k=0..floor(n/2), (n-k+1)!*C(n-k)2^(2k-n)/((k+1)!*C(k))}.

Crossrefs

Sequence in context: A306881 A367489 A084661 * A346680 A292500 A228065

Adjacent sequences: A112291 A112292 A112293 * A112295 A112296 A112297

Keyword

easy,nonn

Author

Paul Barry, Sep 01 2005

Status

approved