OFFSET
1,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).
FORMULA
G.f.: x^2*(1+6*x+x^2) / ((1+x+x^2)*(x-1)^2). - R. J. Mathar, Oct 08 2011
From Wesley Ivan Hurt, Jun 13 2016: (Start)
a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
a(n) = (24*n-24+15*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*Pi*n/3))/9.
a(3k) = 8k-1, a(3k-1) = 8k-7, a(3k-2) = 8k-8. (End)
MAPLE
A047523:=n->(24*n-24+15*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*Pi*n/3))/9: seq(A047523(n), n=1..100); # Wesley Ivan Hurt, Jun 13 2016
MATHEMATICA
Select[Range[0, 150], MemberQ[{0, 1, 7}, Mod[#, 8]] &] (* Wesley Ivan Hurt, Jun 13 2016 *)
LinearRecurrence[{1, 0, 1, -1}, {0, 1, 7, 8}, 100] (* Vincenzo Librandi, Jun 14 2016 *)
PROG
(Magma) [n : n in [0..150] | n mod 8 in [0, 1, 7]]; // Wesley Ivan Hurt, Jun 13 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved