A026958 a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026615.

1, 10, 69, 340, 1476, 6074, 24419, 97136, 384428, 1517422, 5981070, 23556746, 92743296, 365078146, 1437124303, 5657887016, 22279053380, 87749051950, 345704345066, 1362361338578, 5370436417996, 21176724230654, 83529562154498, 329573910914930, 1300752571946396

Offset

2,2

Links

G. C. Greubel, Table of n, a(n) for n = 2..1000

Formula

a(n) = binomial(2*n, n+2)*(49*n^4 - 154*n^3 + 209*n^2 - 200*n + 108)/(24*binomial(2*n, 4)) -2*(n^2 - 2*n + 2) + [n=2]. - G. C. Greubel, Jun 17 2024

Mathematica

Table[Binomial[2*n, n+2]*(49*n^4 -154*n^3 +209*n^2 -200*n +108)/(24* Binomial[2*n, 4]) -2*(n^2-2*n+2) + Boole[n==2], {n, 2, 40}] (* G. C. Greubel, Jun 17 2024 *)

Prog

(Magma) [n eq 2 select 1 else Binomial(2*n, n+2)*(49*n^4 -154*n^3 + 209*n^2 -200*n +108)/(24*Binomial(2*n, 4)) -2*(n^2-2*n+2): n in [2..40]]; // G. C. Greubel, Jun 17 2024
(SageMath) [binomial(2*n, n+2)*(49*n^4 -154*n^3 +209*n^2 -200*n +108 )/(24*binomial(2*n, 4)) -2*(n^2-2*n+2) +int(n==2) for n in range(2, 41)] # G. C. Greubel, Jun 17 2024

Crossrefs

Cf. A026615, A026616, A026617, A026618, A026619, A026620, A026621.

Cf. A026622, A026623, A026624, A026625, A026956, A026957, A026959.

Cf. A026960.

Sequence in context: A219466 A330352 A321060 * A026988 A081280 A038806

Adjacent sequences: A026955 A026956 A026957 * A026959 A026960 A026961

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Sean A. Irvine, Oct 20 2019

Status

approved