A152053 a(n) = A144433(3n+1) + A144433(3n+2) + A144433(3n+3).

27, 36, 81, 72, 135, 108, 189, 144, 243, 180, 297, 216, 351, 252, 405, 288, 459, 324, 513, 360, 567, 396, 621, 432, 675, 468, 729, 504, 783, 540, 837, 576, 891, 612, 945, 648, 999, 684, 1053, 720, 1107

Offset: 0

Author

Paul Curtz, Nov 22 2008

Keywords

• nonn
• easy

Comments

All terms are multiples of 9.

Links

• Index entries for linear recurrences with constant coefficients, signature (0, 2, 0, -1).

Crossrefs

Cf. A106933, A144433.

Programs

Mathematica

Table[(9/2)(5 + (-1)^n)(n + 1), {n, 0, 40}] (* Jean-François Alcover, Feb 02 2019 *)
LinearRecurrence[{0,2,0,-1},{27,36,81,72},50] (* Harvey P. Dale, Nov 07 2019 *)

PARI

a(n) = 45*(n+1)/2 + 9*(-1)^n*(n+1)/2 \\ Jianing Song, Feb 04 2019

Formula

From R. J. Mathar, May 21 2009: (Start)

G.f.: 9*(3+4*x+3*x^2)/((x-1)^2*(1+x)^2).

a(n) = 45*(n+1)/2 + 9*(-1)^n*(n+1)/2. (End)

a(n) = 9*A106833(n+1). - Jean-François Alcover, Feb 02 2019, after Paul Curtz

a(n+4) = 2*a(n+2) - a(n). - Jianing Song, Feb 04 2019

Extensions

Edited by R. J. Mathar, May 21 2009