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 A117263 Row sums of triangle A117262; also, self-convolution of A117264. 3
 1, 2, 7, 64, 1729, 140050, 34032151, 24809438080, 54258241080961, 355988319732185122, 7006918097288599756327, 413751506726794527011353024, 73294838162131470076480154142529 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..12. FORMULA a(n) = Sum_{k=0..n} 3^( n*(n-1)/2 - k*(k-1)/2 ). G.f. A(x) satisfies: A(x) = 1/(1 - x) + x * A(3*x). - Ilya Gutkovskiy, Jun 06 2020 PROG (PARI) a(n)=sum(k=0, n, 3^((n-k)*(n+k-1)/2)) CROSSREFS Cf. A117261, A117262, A117264. Sequence in context: A346781 A011821 A366705 * A046855 A179043 A116985 Adjacent sequences: A117260 A117261 A117262 * A117264 A117265 A117266 KEYWORD nonn AUTHOR Paul D. Hanna, Mar 14 2006 STATUS approved

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Last modified August 13 20:02 EDT 2024. Contains 375144 sequences. (Running on oeis4.)