OFFSET
0,1
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
N. S. Mendelsohn, Permutations with confined displacement, Canad. Math. Bull., 4 (1961), 29-38.
Index entries for linear recurrences with constant coefficients, signature (2, 0, -1).
FORMULA
3*A000381.
G.f.: 3*(2-x-2*x^2)/((x^2+x-1)*(x-1)). - Vincenzo Librandi, Jul 01 2017
MATHEMATICA
Join[{6}, Table[3 Fibonacci[n+3] + 3, {n, 0, 40}]] (* or *) CoefficientList[Series[3 (2 - x - 2 x^2) / ((x^2 + x - 1) (x - 1)), {x, 0, 33}], x] (* Vincenzo Librandi, Jul 01 2017 *)
PROG
(Magma) [6] cat [3*Fibonacci(n+3)+3: n in [0..40]]; // Vincenzo Librandi, Jul 01 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved