A026702 a(n) = Sum_{k=0..floor(n/2)} T(n-k, k), T given by A026692.

1, 1, 2, 3, 5, 8, 15, 26, 48, 79, 137, 223, 403, 689, 1251, 2088, 3647, 6028, 10775, 18386, 33010, 55460, 96916, 161705, 287199, 490430, 873964, 1475256, 2575673, 4325448, 7646036, 13072664, 23169478, 39254755, 68456542

Offset

0,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Mathematica

T[_, 0] = 1; T[n_, n_] = 1; T[n_, k_] /; EvenQ[k] && 1 <= k/2 <= Floor[n/4] || EvenQ[n - k] && 1 <= (n - k)/2 <= Floor[n/4] := T[n, k] = T[n - 1, k - 1] + T[n - 2, k - 1] + T[n - 1, k]; T[n_, k_] := T[n, k] = T[n - 1, k - 1] + T[n - 1, k];
a[n_] := Sum[T[n - k, k], {k, 0, Floor[n/2]}];
Table[a[n], {n, 0, 34}] (* Jean-François Alcover, Jul 02 2017 *)

Crossrefs

Sequence in context: A177486 A006982 A054539 * A000047 A101172 A192677

Adjacent sequences: A026699 A026700 A026701 * A026703 A026704 A026705

Keyword

nonn

Author

Clark Kimberling

Status

approved