A054127 a(1) = 2; a(n) = 9*2^(n-2) - n - 2, n>1.

2, 5, 13, 30, 65, 136, 279, 566, 1141, 2292, 4595, 9202, 18417, 36848, 73711, 147438, 294893, 589804, 1179627, 2359274, 4718569, 9437160, 18874343, 37748710, 75497445, 150994916, 301989859, 603979746, 1207959521

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• easy

Comments

Second column of A054126.

Links

• Index entries for linear recurrences with constant coefficients, signature (4,-5,2).

Crossrefs

Cf. A054126.

Programs

Mathematica

Join[{2},Table[9*2^(n-2)-n-2,{n,2,30}]] (* Harvey P. Dale, Jul 16 2020 *)
LinearRecurrence[{4,-5,2},{2,5,13,30},30] (* Harvey P. Dale, Aug 01 2021 *)

Formula

a(n) = A054126(n, 1).

G.f.: x * (2-x) * (1-x+x^2) / ( (1-x)^2 * (1-2*x) ). - Joerg Arndt, Dec 01 2014