OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).
FORMULA
G.f.: x*(1 + 2*x + 8*x^2 + x^3)/((1 - x)^2*(1 + x + x^2)).
a(n) = a(n-1) + a(n-3) - a(n-4) for n>12.
a(n) = 2*a(n-1) - 2*a(n-2) + 2*a(n-3) - 2*a(n-4) + 2*a(n-5) - a(n-6) for n>6.
a(n) = 2*n + 6*floor(n/3) - 1. - Bruno Berselli, Jun 13 2018
MATHEMATICA
Table[2 n + 6 Floor[n/3] - 1, {n, 1, 60}] (* Bruno Berselli, Jun 13 2018 *)
LinearRecurrence[{1, 0, 1, -1}, {1, 3, 11, 13}, 60] (* Harvey P. Dale, Mar 15 2023 *)
PROG
(Magma) [n: n in [0..300] | n mod 12 in [1, 3, 11]]; // Bruno Berselli, Jun 13 2018
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Vincenzo Librandi, Jun 12 2018
EXTENSIONS
Edited by Bruno Berselli, Jun 13 2018
STATUS
approved