A015566 Expansion of x/(1 - 7*x - 9*x^2).

0, 1, 7, 58, 469, 3805, 30856, 250237, 2029363, 16457674, 133467985, 1082394961, 8777976592, 71187390793, 577313524879, 4681881191290, 37968990062941, 307919861162197, 2497159938701848, 20251398321372709, 164234227697925595

Offset: 0

Author

Olivier Gérard

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (7,9).

Programs

Magma

[n le 2 select n-1 else 7*Self(n-1) + 9*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 14 2012

Mathematica

Join[{a=0,b=1},Table[c=7*b+9*a;a=b;b=c,{n,100}]] (* Vladimir Joseph Stephan Orlovsky, Jan 17 2011 *)
LinearRecurrence[{7, 9}, {0, 1}, 30] (* Vincenzo Librandi, Nov 14 2012 *)

PARI

x='x+O('x^30); concat([0], Vec(x/(1-7*x-9*x^2))) \\ G. C. Greubel, Dec 31 2017

Sage

[lucas_number1(n,7,-9) for n in range(0, 20)] # Zerinvary Lajos, Apr 24 2009

Formula

a(n) = 7*a(n-1) + 9*a(n-2).