A081741 Numbers k that divide A005554(k) (the sum of consecutive Motzkin numbers).

1, 2, 3, 6, 9, 18, 27, 54, 81, 102, 126, 162, 189, 243, 369, 486, 567, 729, 1071, 1134, 1323, 1458, 1462, 1539, 2187, 2538, 2889, 3213, 4374, 4617, 6561, 7749, 8262, 8667, 13122, 14238, 15498, 19683, 24786, 27702, 28994, 32319, 34263, 39366, 40838

Offset: 1

Author

Benoit Cloitre, Apr 07 2003

Keywords

• nonn

Comments

All the powers of 3 (A000244) are in the sequence.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..165

Crossrefs

Cf. A000244, A001006, A005554.

Programs

Mathematica

s = {1, 2}; k1 = 1; k2 = 2; Do[k3 = (2*n*k2 + (3*n - 9)*k1)/(n + 1); If[Divisible[k3, n], AppendTo[s, n]]; k1 = k2; k2 = k3, {n, 3, 42000}]; s (* Amiram Eldar, Jun 28 2022 *)