OFFSET
0,3
COMMENTS
a(n) is also the coefficient of x^(n-1) in the bivariate Fibonacci polynomials F(n)(x,y)=xF(n-1)(x,y)+yF(n-2)(x,y),F(0)(x,y)=0,F(1)(x,y)=1, when we write 13x for x and -36x^2 for y. - Mario Catalani (mario.catalani(AT)unito.it), Dec 09 2002
LINKS
R. Flórez, R. A. Higuita and A. Mukherjee, Alternating Sums in the Hosoya Polynomial Triangle, Article 14.9.5 Journal of Integer Sequences, Vol. 17 (2014).
Index entries for linear recurrences with constant coefficients, signature (13,-36).
FORMULA
G.f.: x/((1-4*x)*(1-9*x)). a(n)=13*a(n-1)-36*a(n-2).
a(n) = A015441(2*n).
MATHEMATICA
Join[{a=0, b=1}, Table[c=13*b-36*a; a=b; b=c, {n, 60}]](*and/or*)f[n_]:=(9^n-4^n)/5; f[Range[0, 60]] (* Vladimir Joseph Stephan Orlovsky, Feb 01 2011 *)
PROG
(PARI) a(n)=(9^n-4^n)/5
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved