A158083 a(n) = Fibonacci(n+3) for n < 5 and 9*n - 15 otherwise.

2, 3, 5, 8, 13, 30, 39, 48, 57, 66, 75, 84, 93, 102, 111, 120, 129, 138, 147, 156, 165, 174, 183, 192, 201, 210, 219, 228, 237, 246, 255, 264, 273, 282, 291, 300, 309, 318, 327, 336, 345, 354, 363, 372, 381, 390, 399, 408, 417, 426, 435

Offset

0,1

Comments

This sequence is a possible answer to Marus du Satoy's puzzle sequence, see reference.

References

Marcus Du Sautoy, Symmetry: A Journey into the Patterns of Nature, Harper (March 11, 2008), page 96.

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Formula

a(n) = a(n-1) + 9 for n > 5, a(n-1) + a(n-2) + 9 for n = 5, and Fibonacci(n+3) for n < 5.

From R. J. Mathar, Apr 10 2009: (Start)

G.f.: (2 -x +x^2 +x^3 +2*x^4 +12*x^5 -8*x^6)/(1-x)^2.

a(n) = 9*n - 15, n>4. (End)

Mathematica

a[n_]:= a[n]= If[n<5, Fibonacci[n+3], If[n==5, a[n-1] +a[n-2] +9, a[n-1] +9]];
Table[a[n], {n, 0, 50}] (* modified by G. C. Greubel, May 14 2021 *)
Join[{2, 3, 5, 8, 13}, NestList[#+9&, 30, 50]] (* Harvey P. Dale, Nov 18 2012 *)
Table[If[n<5, Fibonacci[n+3], 9*n-15], {n, 0, 50}] (* G. C. Greubel, May 14 2021 *)

Prog

(Magma)
A158083:= func< n | n lt 5 select Fibonacci(n+3) else 3*(3*n-5) >;
[A158083(n): n in [0..50]]; // G. C. Greubel, May 14 2021
(Sage)
def A158083(n): return fibonacci(n+3) if (n<5) else 3*(3*n-5)
[A158083(n) for n in (0..50)] # G. C. Greubel, May 14 2021

Crossrefs

Sequence in context: A132915 A030036 A115212 * A042163 A273045 A014259

Adjacent sequences: A158080 A158081 A158082 * A158084 A158085 A158086

Keyword

nonn,easy

Author

Roger L. Bagula, Mar 12 2009

Extensions

Edited by G. C. Greubel, May 14 2021

Status

approved