A377368 a(n) = A255978(n) + 1.

1, 2, 2, 5, 6, 10, 17, 26, 42, 69, 110, 178, 289, 466, 754, 1221, 1974, 3194, 5169, 8362, 13530, 21893, 35422, 57314, 92737, 150050, 242786, 392837, 635622, 1028458, 1664081, 2692538, 4356618, 7049157, 11405774, 18454930, 29860705, 48315634, 78176338

Offset: 0

Author

Sean A. Irvine, Dec 27 2024

Keywords

• nonn
• easy

Links

• Paolo Xausa, Table of n, a(n) for n = 0..1000
• Daniel Hardisky, Math Puzzle, Short Mathematical Idea Facebook Group, Oct 19 2024.
• Index entries for linear recurrences with constant coefficients, signature (1,1,1,-1,-1).

Crossrefs

Cf. A255978.

Programs

Mathematica

LinearRecurrence[{1, 1, 1, -1, -1}, {1, 2, 2, 5, 6}, 50] (* Paolo Xausa, Dec 30 2024 *)

Formula

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

a(n) = a(n-1) + a(n-2) + a(n-3) - a(n-4) - a(n-5) for n>4.