OFFSET
3,1
LINKS
Colin Barker, Table of n, a(n) for n = 3..1000
Eric Weisstein's World of Mathematics, Hamiltonian Path
Eric Weisstein's World of Mathematics, Prism Graph
Index entries for linear recurrences with constant coefficients, signature (2,1,-4,1,2,-1).
FORMULA
a(n) = A124350(n)/2.
From Colin Barker, Jul 19 2019: (Start)
G.f.: 2*x^3*(15 + 6*x - 22*x^2 + 8*x^3 + 11*x^4 - 6*x^5) / ((1 - x)^4*(1 + x)^2).
a(n) = n*(3 + (-1)^n + 2*n^2) / 2.
a(n) = 2*a(n-1) + a(n-2) - 4*a(n-3) + a(n-4) + 2*a(n-5) - a(n-6) for n>8.
(End)
MATHEMATICA
LinearRecurrence[{2, 1, -4, 1, 2, -1}, {30, 72, 130, 228, 350, 528}, 50] (* Harvey P. Dale, Jun 20 2021 *)
PROG
(PARI) Vec(2*x^3*(15 + 6*x - 22*x^2 + 8*x^3 + 11*x^4 - 6*x^5) / ((1 - x)^4*(1 + x)^2) + O(x^30)) \\ Colin Barker, Jul 19 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, May 14 2019
EXTENSIONS
More terms from Colin Barker, Jul 19 2019
STATUS
approved