OFFSET
1,1
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
From Chai Wah Wu, May 30 2016: (Start)
a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
G.f.: x*(x^3 + x^2 + x + 5)/(x^4 - x^3 - x + 1). (End)
a(n) = (8*n-10*sin(2*Pi*(n+1)/3)/sqrt(3)+2)/3. - Ilya Gutkovskiy, May 30 2016
a(n) = 8*floor((n-1)/3)+((n-1) mod 3)+5. - David A. Corneth, May 30 2016
a(3k) = 8k-1, a(3k-1) = 8k-2, a(3k-2) = 8k-3. - Wesley Ivan Hurt, Jun 10 2016
MAPLE
A047574:=n->8*floor((n-1)/3)+((n-1) mod 3)+5: seq(A047574(n), n=1..100); # Wesley Ivan Hurt, Jun 10 2016
MATHEMATICA
Select[Range[200], MemberQ[{5, 6, 7}, Mod[#, 8]] &] (* Vincenzo Librandi, May 30 2016 *)
LinearRecurrence[{1, 0, 1, -1}, {5, 6, 7, 13}, 60] (* Harvey P. Dale, Jul 29 2016 *)
PROG
(Magma) [n: n in [0..200] | n mod 8 in [5..7]]; // Vincenzo Librandi, May 30 2016
(PARI) a(n)=8 * (n-1)\3 + (n-1)%3 + 5 \\ David A. Corneth, May 30 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved