A027109 a(n) = Sum_{k=0..n} T(n,k) * T(n,n+k), with T given by A027082.

1, 2, 6, 29, 131, 619, 3013, 14854, 73996, 372023, 1883369, 9591012, 49091034, 252371780, 1302419484, 6744389329, 35031370911, 182457629783, 952674694705, 4985494458892, 26143834054498, 137358293523986, 722938114992478

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Mathematica

T[_, 0] = T[_, 1] = T[_, 2] = 1;
T[n_, k_] := T[n, k] = If[k < 2n, T[n-1, k-3] + T[n-1, k-2] + T[n-1, k-1], T[n-1, 2n-3] + T[n-1, 2n-2]];
a[n_] := Sum[T[n, k] T[n, n+k], {k, 0, n}];
a /@ Range[0, 22] (* Jean-François Alcover, Sep 26 2020 *)

Crossrefs

Cf. A027082.

Sequence in context: A368003 A368143 A284594 * A348764 A107375 A302863

Adjacent sequences: A027106 A027107 A027108 * A027110 A027111 A027112

Keyword

nonn

Author

Clark Kimberling

Status

approved