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A188476 Diagonal sums of number triangle A188474. 2
1, 1, 2, 6, 12, 27, 65, 150, 353, 843, 2014, 4843, 11713, 28433, 69292, 169470, 415754, 1022868, 2523120, 6238645, 15459561, 38387191, 95497612, 237989801, 594062697, 1485141397, 3718116380, 9320941698, 23396109986, 58795356627, 147920737819 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Hankel transform is A188477(n+1).

LINKS

Table of n, a(n) for n=0..30.

FORMULA

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

Conjecture: (n+3)*a(n) +(-4*n-9)*a(n-1) +n*a(n-2) -3*a(n-3) +3*(5*n+1)*a

(n-4) +6*(n)*a(n-5) +6*(n-1)*a(n-6) +4*(-n+3)*a(n-7)=0. - R. J. Mathar, Dec 03 2014

CROSSREFS

Sequence in context: A059078 A335712 A166963 * A155583 A140853 A185961

Adjacent sequences:  A188473 A188474 A188475 * A188477 A188478 A188479

KEYWORD

nonn,easy

AUTHOR

Paul Barry, Apr 01 2011

STATUS

approved

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Last modified July 26 20:29 EDT 2021. Contains 346295 sequences. (Running on oeis4.)