A274200 Limiting reverse row of the array A274193.

1, 1, 1, 2, 2, 3, 4, 5, 7, 9, 12, 16, 20, 27, 35, 45, 60, 77, 101, 132, 170, 223, 289, 375, 490, 634, 826, 1074, 1392, 1813, 2352, 3055, 3973, 5154, 6700, 8702, 11296, 14681, 19058, 24754, 32156, 41747, 54232, 70425, 91451, 118786, 154241, 200319, 260157

Offset

1,4

Comments

The triangular array (g(n,k)) at A274193 is defined as follows: g(n,k) = 1 for n >= 0; g(n,k) = 0 if k > n; g(n,k) = g(n-1,k-1) + g(n-1,3) for n > 0, k > 1.

Links

Table of n, a(n) for n=1..49.

Example

Row g(9,k):  1,4,4,4,3,2,2,1,1,1; the reversal is
1,1,1,2,2,3,4,4,4,1,..., which agrees with A274200 up to the first 7 terms.

Mathematica

g[n_, 0] = g[n, 0] = 1;
g[n_, k_] := g[n, k] = If[k > n, 0, g[n - 1, k - 1] + g[n - 1, 3 k]];
z = 300; w = Reverse[Table[g[z, k], {k, 0, z}]];
Take[w, z/3]

Crossrefs

Cf. A274193, A274199, A274201.

Sequence in context: A225501 A117298 A369571 * A018052 A018124 A124745

Adjacent sequences: A274197 A274198 A274199 * A274201 A274202 A274203

Keyword

nonn,easy

Author

Clark Kimberling, Jun 16 2016

Status

approved