A191467 9^n - 7^n.

0, 2, 32, 386, 4160, 42242, 413792, 3959426, 37281920, 347066882, 3204309152, 29403732866, 268588249280, 2444976817922, 22198569382112, 201143570584706, 1819787258282240, 16444551185679362, 148466221699088672, 1339452822487618946

Offset: 0

Author

Vincenzo Librandi, Jun 03 2011

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..300
• Index entries for linear recurrences with constant coefficients, signature (16,-63).

Crossrefs

Cf. A118004, A016178, A016185, A059410, A139745, A191467.

Programs

Magma

[9^n - 7^n: n in [0..20]]:

Mathematica

Table[9^n-7^n,{n,0,20}] (* or *) LinearRecurrence[{16,-63},{0,2},20] (* Harvey P. Dale, Jun 21 2014 *)
CoefficientList[Series[2 x/((1 - 7 x) (1 - 9 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 05 2014 *)

PARI

a(n)=9^n-7^n \\ Charles R Greathouse IV, Jun 08 2011

Formula

a(n) = 16*a(n-1) - 63*a(n-2).

G.f.: 2*x/((1-7*x)*(1-9*x)). - Vincenzo Librandi, Oct 05 2014

a(n+1) = 2*A016178(n). - Vincenzo Librandi, Oct 05 2014