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

1,2

Comments

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

Links

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

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 *)

Crossrefs

Cf. A000244, A001006, A005554.

Sequence in context: A206100 A178940 A018264 * A035522 A018311 A018481

Adjacent sequences: A081738 A081739 A081740 * A081742 A081743 A081744

Keyword

nonn

Author

Benoit Cloitre, Apr 07 2003

Status

approved