A155485 a(n) = 5^n + (1 - 4^n)/3.

1, 4, 20, 104, 540, 2784, 14260, 72664, 368780, 1865744, 9416100, 47430024, 238548220, 1198333504, 6014037140, 30159664184, 151156234860, 757212830064, 3791790773380, 18981860359144, 95000927764700, 475371142699424, 2378321729000820, 11897472707018904

Offset: 0

Author

Paul Curtz, Jan 23 2009

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (10, -29, 20).

Programs

Magma

[5^n+(1-4^n)/3: n in [0..30]]; // Vincenzo Librandi, Aug 07 2011

Formula

a(n) = A000351(n) - A001045(2n).

a(n) = 10a(n-1) - 29a(n-2) + 20a(n-3), as in A097165.

From R. J. Mathar, Feb 27 2009: (Start)

G.f.: (1-3x)^2/((1-x)(1-4x)(1-5x)).

a(n) = A097165(n) - 3*A097165(n-1). (End)

Extensions

Edited, Lava definition adopted, and extended by R. J. Mathar, Feb 27 2009