OFFSET
0,3
COMMENTS
Partial sums of A092808.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,5,0,-4)
FORMULA
a(n) = 5*2^n/6+(-2)^n/6+(-1)^n/6-1/6.
a(2*n) = 4^n = A000302(n).
a(2*n+1) = (4*4^n-1)/3 = A002450(n+1).
From Colin Barker, Sep 09 2016: (Start)
a(n) = 5*a(n-2)-4*a(n-4) for n>3.
G.f.: (1+x-x^2) / ((1-x)*(1+x)*(1-2*x)*(1+2*x))
(End)
PROG
(PARI) Vec((1+x-x^2)/((1-x)*(1+x)*(1-2*x)*(1+2*x)) + O(x^40)) \\ Colin Barker, Sep 09 2016
(PARI) a(n) = if(n%2, 2, 3)<<n \ 3 \\ Charles R Greathouse IV, Sep 09 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Mar 10 2004
STATUS
approved