A171237 a(0)=2, a(1)=3, a(n) = 3 + a(n-1) + a(n-2) for n >= 2.

2, 3, 8, 14, 25, 42, 70, 115, 188, 306, 497, 806, 1306, 2115, 3424, 5542, 8969, 14514, 23486, 38003, 61492, 99498, 160993, 260494, 421490, 681987, 1103480, 1785470, 2888953, 4674426, 7563382, 12237811, 19801196, 32039010, 51840209, 83879222

Offset

0,1

Comments

a(n) gives the time complexity of a recursive Fibonacci algorithm.

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

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

Formula

a(0)=2, a(1)=3, a(n) = 3 + a(n-1) + a(n-2) n >= 2.

From R. J. Mathar, Dec 06 2009: (Start)

a(n) = 2*a(n-1) - a(n-3) = A022095(n+1) - 3.

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

Mathematica

LinearRecurrence[{2, 0, -1}, {2, 3, 8}, 50] (* Harvey P. Dale, Mar 19 2020 *)

Crossrefs

Sequence in context: A368855 A022951 A247124 * A173149 A128305 A328881

Adjacent sequences: A171234 A171235 A171236 * A171238 A171239 A171240

Keyword

nonn,easy

Author

Manfred Jackel (jkl(AT)uni-koblenz.de), Dec 05 2009

Status

approved