OFFSET
1,1
LINKS
FORMULA
a(n) = ((26+7*sqrt(2))*(3-2*sqrt(2))^n+(26-7*sqrt(2))*(3+2*sqrt(2))^n)/4.
G.f.: x*(25-13*x)/(1-6*x+x^2).
Limit_{n -> oo} a(n)/a(n-1) = 3+2*sqrt(2).
MATHEMATICA
LinearRecurrence[{6, -1}, {25, 137}, 30] (* Harvey P. Dale, Jan 02 2019 *)
PROG
(PARI) {m=19; v=concat([25, 137], vector(m-2)); for(n=3, m, v[n]=6*v[n-1]-v[n-2]); v}
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, Feb 09 2009
STATUS
approved