OFFSET
1,1
LINKS
FORMULA
a(n) = (5-3*(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2.
G.f.: x*(4+3*x)/(1-3*x^2).
a(n) = A074324(n+1) = A166552(n+1) = 3^floor(n/2)*4^(n%2), where n%2 = 0 for n even, 1 for n odd. - M. F. Hasler, Dec 03 2014
PROG
(Magma) [ n le 2 select 5-n else 3*Self(n-2): n in [1..34] ];
(PARI) a(n)=3^(n\2)*4^(n%2) \\ M. F. Hasler, Dec 03 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Jul 13 2009
EXTENSIONS
G.f. corrected by Klaus Brockhaus, Sep 18 2009
STATUS
approved