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
Keywords
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Programs
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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 *)