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A109957 Diagonal sums of number triangle A109956. 1
1, -1, 4, -16, 74, -368, 1926, -10455, 58333, -332489, 1927761, -11334128, 67416570, -404956315, 2453012916, -14967587873, 91910798556, -567566697627, 3522334450512, -21957276973619, 137425078658354, -863229921626723, 5440215989173113, -34388244134246836 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..23.

FORMULA

G.f. : g/(1-f) where f/(1-f)^3=x and g=1-f; a(n)=(-1)^n*sum{k=0..floor(n/2), ((3k+1)/(2n-k+1))*binomial(3n-3k, n-2k)}.

CROSSREFS

Sequence in context: A344248 A301455 A214372 * A306495 A331159 A101205

Adjacent sequences: A109954 A109955 A109956 * A109958 A109959 A109960

KEYWORD

easy,sign

AUTHOR

Paul Barry, Jul 06 2005

STATUS

approved

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Last modified February 4 17:27 EST 2023. Contains 360059 sequences. (Running on oeis4.)