A147839 a(n)=9*a(n-1)-7*a(n-2), a(0)=1, a(1)=7 .

1, 7, 56, 455, 3703, 30142, 245357, 1997219, 16257472, 132336715, 1077228131, 8768696174, 71377668649, 581018144623, 4729519621064, 38498549577215, 313380308847487, 2550932932586878, 20764734231349493, 169026077554037291

Offset: 0

Author

Philippe Deléham, Nov 14 2008

Keywords

• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (9,-7).

Programs

Mathematica

LinearRecurrence[{9,-7},{1,7},30] (* Harvey P. Dale, Nov 30 2019 *)

Formula

a(n)=Sum_{k, 0<=k<=n}A147703(n,k)*6^k . G.f.: (1-2x)/(1-9x+7*x^2).

a(n)= ((53+5*sqrt(53))/106)*(4.5+0.5*sqrt(53))^n + ((53-5*sqrt(53))/106)*(4.5-0.5*sqrt(53))^n [From Richard Choulet, Nov 20 2008]