OFFSET
1,1
COMMENTS
Extended to a(1)-a(2) using the formula/recurrence.
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Antiprism Graph
Eric Weisstein's World of Mathematics, Hamiltonian Cycle
Index entries for linear recurrences with constant coefficients, signature (3,-1,-2,0,1).
FORMULA
a(n) = A124353(n)/2.
From Colin Barker, Jul 12 2020: (Start)
G.f.: x*(3 - 8*x^2 - 4*x^3 + 3*x^4) / ((1 - x)^2*(1 - x - 2*x^2 - x^3)).
a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3) + a(n-5) for n>5.
(End)
MATHEMATICA
LinearRecurrence[{3, -1, -2, 0, 1}, {3, 9, 16, 29, 56}, 40] (* Harvey P. Dale, Aug 06 2020 *)
PROG
(PARI) Vec(x*(3 - 8*x^2 - 4*x^3 + 3*x^4) / ((1 - x)^2*(1 - x - 2*x^2 - x^3)) + O(x^35)) \\ Colin Barker, Jul 12 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, May 04 2019
STATUS
approved