OFFSET
1,6
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
R. S. Booth, An odd order search problem, SIAM J. Algebraic Discrete Methods 3 (1982), no. 1, 135--143. MR0644964 (83d:90106). See sequence U(n).
Index entries for linear recurrences with constant coefficients, signature (0,0,0,2,0,0,0,0,0,0,0,1).
FORMULA
G.f.: x*(x^12-x^11+x^9-x^8+x^4-x^3-x^2-x-1) / (x^12+2*x^4-1). - Colin Barker, Apr 18 2014
MAPLE
U:=proc(n) option remember; if n <= 5 then 1
elif n <= 8 then 2
elif n <= 10 then 3
elif n = 11 then 4
elif n = 12 then 5
elif n = 13 then 6
else 2*U(n-4)+U(n-12); fi; end;
[seq(U(n), n=1..60)];
MATHEMATICA
CoefficientList[Series[(x^12 - x^11 + x^9 - x^8 + x^4 - x^3 - x^2 - x - 1)/(x^12 + 2 x^4 - 1), {x, 0, 40}], x] (* Vincenzo Librandi, Apr 19 2014 *)
LinearRecurrence[{0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 1}, {1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5, 6}, 70] (* Harvey P. Dale, Mar 30 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 07 2014
STATUS
approved