OFFSET
1,2
COMMENTS
Contains only odd numbers.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..150
Index entries for linear recurrences with constant coefficients, signature (4,0,-3).
FORMULA
G.f.: -x*(-1+ x + x ^2) / ( (x-1)*(3*x^2 + 3*x - 1) ). - R. J. Mathar, Oct 04 2011
a(n) = (3 + 2*A108306(n))/15. - R. J. Mathar, Oct 04 2011
MATHEMATICA
With[{c=(3+Sqrt[21])/2}, NestList[Floor[c*#]&, 1, 30]] (* Harvey P. Dale, Apr 23 2014 *)
PROG
(Magma) I:=[1, 3, 11]; [n le 3 select I[n] else 4*Self(n-1)-3*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Oct 05 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Oct 03 2011
STATUS
approved