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A184884 Diagonal sums of number triangle A184883. 2
1, 1, 2, 6, 11, 27, 60, 132, 301, 669, 1502, 3370, 7543, 16919, 37912, 84968, 190457, 426841, 956698, 2144238, 4805827, 10771315, 24141588, 54108332, 121272549, 271806901, 609198390, 1365390546, 3060236911, 6858880431, 15372743856, 34454786384, 77223188593, 173079605553, 387921692082, 869445237846 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..35.

Index entries for linear recurrences with constant coefficients, signature (1,2,2,-1,1).

FORMULA

G.f.: (1-x^2)/(1-x-2x^2-2x^3+x^4-x^5).

a(n)=sum{k=0..floor(n/2), sum{j=0..k, C(2n-4k,j)*C(k,j)2^j}}.

CROSSREFS

Sequence in context: A033304 A091622 A191315 * A275222 A165821 A296390

Adjacent sequences:  A184881 A184882 A184883 * A184885 A184886 A184887

KEYWORD

nonn,easy

AUTHOR

Paul Barry, Jan 24 2011

STATUS

approved

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Last modified October 14 16:48 EDT 2019. Contains 328022 sequences. (Running on oeis4.)