A169687 a(n) = 3^n - 3*2^(n-2).

6, 21, 69, 219, 681, 2091, 6369, 19299, 58281, 175611, 528369, 1588179, 4770681, 14324331, 42997569, 129041859, 387223881, 1161868251, 3485997969, 10458780339, 31377913881, 94136887371, 282416953569, 847263443619, 2541815496681, 7625496821691, 22876591128369

Offset

2,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 2..1000

Prog

(Magma) [3^n-3*2^(n-2): n in [2..35]]; // Vincenzo Librandi, Jun 30 2011

Crossrefs

Arises in the analysis of A169688.

Sequence in context: A364636 A318943 A200761 * A302448 A101904 A022814

Adjacent sequences: A169684 A169685 A169686 * A169688 A169689 A169690

Keyword

nonn,easy

Author

N. J. A. Sloane, Apr 14 2010

Status

approved