OFFSET
0,3
COMMENTS
For n>=2, a(n) is the number of oriented rational links with crossing number n and deficiency 0.
LINKS
Yuanan Diao, Michael Finney, and Dawn Ray, The number of oriented rational links with a given deficiency number, arXiv:2007.02819 [math.GT], 2020. See Remark 5 p. 16.
Index entries for linear recurrences with constant coefficients, signature (1,2,-1,0,-1,-1).
FORMULA
G.f.: -(3*x^4-x^3+x-1)/((x^2+x-1)*(x^4+x^2-1)). - Alois P. Heinz, Jul 07 2020
PROG
(PARI) a(n) = fibonacci(n-1) + fibonacci(n\2);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Marcus, Jul 07 2020
STATUS
approved