A022131 Fibonacci sequence beginning 4, 11.

4, 11, 15, 26, 41, 67, 108, 175, 283, 458, 741, 1199, 1940, 3139, 5079, 8218, 13297, 21515, 34812, 56327, 91139, 147466, 238605, 386071, 624676, 1010747, 1635423, 2646170, 4281593, 6927763, 11209356, 18137119, 29346475, 47483594, 76830069, 124313663

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Tanya Khovanova, Recursive Sequences
• Index entries for linear recurrences with constant coefficients, signature (1, 1).

Crossrefs

Cf. A000032.

Programs

Mathematica

a={};b=4;c=11;AppendTo[a, b];AppendTo[a, c];Do[b=b+c;AppendTo[a, b];c=b+c;AppendTo[a, c], {n, 4!}];a (* Vladimir Joseph Stephan Orlovsky, Sep 17 2008 *)
LinearRecurrence[{1,1},{4,11},40] (* Harvey P. Dale, May 08 2018 *)

Formula

G.f.: (4+7x)/(1-x-x^2). - Philippe Deléham, Nov 19 2008

a(n) = ((10 + 9*sqrt(5))/5)*((1 + sqrt(5))/2)^n + ((10 - 9*sqrt(5))/5)*((1 - sqrt(5))/2)^n starting at n=0. - Bogart B. Strauss, Oct 27 2013