OFFSET
0,1
REFERENCES
R. K. Guy, personal communication.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3, 0, -3, 2).
FORMULA
G.f.: (4-x-3*x^2+3*x^3)/(1-3*x+3*x^3-2*x^4). - Harvey P. Dale, Oct 25 2011
MATHEMATICA
LinearRecurrence[{3, 0, -3, 2}, {4, 11, 30, 81}, 30] (* Harvey P. Dale, Oct 25 2011 *)
PROG
(PARI) my(x='x+O('x^30)); Vec((4-x-3*x^2+3*x^3)/(1-3*x+3*x^3-2*x^4)) \\ G. C. Greubel, Mar 24 2019
(Magma) I:=[4, 11, 30, 81]; [n le 4 select I[n] else 3*Self(n-1)- 3*Self(n-3) +2*Self(n-4): n in [1..30]]; // G. C. Greubel, Mar 24 2019
(Sage) ((4-x-3*x^2+3*x^3)/(1-3*x+3*x^3-2*x^4)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Mar 24 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved