OFFSET
1,2
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (0,3).
FORMULA
a(n) = (3+(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2.
G.f.: x*(1+6*x)/(1-3*x^2).
MATHEMATICA
LinearRecurrence[{0, 3}, {1, 6}, 50] (* G. C. Greubel, May 14 2016 *)
PROG
(Magma) [ n le 2 select 5*n-4 else 3*Self(n-2): n in [1..35] ];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, Oct 13 2009
STATUS
approved