OFFSET
0,3
COMMENTS
a(1) and a(2n) are perfect squares.
LINKS
Index entries for linear recurrences with constant coefficients, signature (3,0,-3,1).
FORMULA
a(n) = 3*a(n-1)-3*a(n-3)+a(n-4). G.f.: 1-x*(x^3-7*x^2+13*x+1) / ((x-1)*(x+1)*(x^2-3*x+1)). - Colin Barker, Sep 01 2013
MATHEMATICA
Table[-4 + 5*Fibonacci[n]^2, {n, 2, 31}] (* Alonso del Arte, Nov 17 2011 *)
PROG
(PARI) Vec(-x*(x^3-7*x^2+13*x+1)/((x-1)*(x+1)*(x^2-3*x+1)) + O(x^100)) \\ Colin Barker, Sep 01 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Nov 17 2011
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Mar 11 2024
STATUS
approved