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 A081197 Diagonal sums of A081130. 2
 0, 0, 0, 1, 4, 13, 44, 162, 643, 2724, 12259, 58423, 293902, 1555743, 8640526, 50222288, 304792741, 1927313470, 12673784445, 86517541197, 612134881624, 4482215342305, 33919417267456, 264951302794510, 2133720505175351 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS G. C. Greubel, Table of n, a(n) for n = 0..500 FORMULA a(n) = Sum_{k=1..n-2} k^(n-k-2)*binomial(n-k, 2). a(n) = Sum_{k=0..n-1} (n-k)^(k-2)*binomial(k, 2). - G. C. Greubel, May 15 2021 MAPLE A081197 := proc(n) add(k^(n-k-2)*binomial(n-k, 2), k=1..n-2) ; end proc: # R. J. Mathar, Feb 13 2015 MATHEMATICA Table[Sum[k^(n-k-2)*Binomial[n-k, 2], {k, n-2}], {n, 0, 30}] (* G. C. Greubel, May 15 2021 *) PROG (Magma) [n lt 3 select 0 else (&+[j^(n-j-2)*Binomial(n-j, 2): j in [1..n-2]]): n in [0..30]]; // G. C. Greubel, May 15 2021 (Sage) [sum( (n-k)^(k-2)*binomial(k, 2) for k in (0..n-1) ) for n in (0..30)] # G. C. Greubel, May 15 2021 CROSSREFS Cf. A081130. Sequence in context: A045652 A149430 A124463 * A005490 A174299 A351028 Adjacent sequences: A081194 A081195 A081196 * A081198 A081199 A081200 KEYWORD easy,nonn AUTHOR Paul Barry, Mar 11 2003 EXTENSIONS Terms corrected by G. C. Greubel, May 15 2021 STATUS approved

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Last modified June 4 00:30 EDT 2023. Contains 363118 sequences. (Running on oeis4.)