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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
OFFSET
0,3
COMMENTS
Hankel transform is A188477(n+1).
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: A335712 A356465 A166963 * A155583 A140853 A185961
KEYWORD
nonn,easy
AUTHOR
Paul Barry, Apr 01 2011
STATUS
approved