OFFSET
1,4
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Black Bishop Graph
Eric Weisstein's World of Mathematics, Graph Cycle
Index entries for linear recurrences with constant coefficients, signature (2,5,-12,-9,30,5,-40,5,30,-9,-12,5,2,-1).
FORMULA
a(n) = 2*a(n-1)+5*a(n-2)-12*a(n-3)-9*a(n-4)+30*a(n-5)+5*a(n-6)-40*a(n-7)+5*a(n-8)+30*a(n-9)-9*a(n-10)-12*a(n-11)+5*a(n-12)+2*a(n-13)-a(n-14).
G.f.: x^4*(15 + 190*x + 738*x^2 + 1986*x^3 + 1328*x^4 + 2590*x^5 - 242*x^6 + 982*x^7 + 81*x^8 + 12*x^9) / ((1 - x)^8*(1 + x)^6). - Colin Barker, Jun 27 2017
MATHEMATICA
Table[(20580 - 15312 n - 27027 n^2 + 28840 n^3 - 10850 n^4 + 2772 n^5 - 658 n^6 + 80 n^7 - 35 (-1)^n (-7 + 2 n) (-84 + 32 n + 83 n^2 - 46 n^3 + 6 n^4))/3360, {n, 20}]
LinearRecurrence[{2, 5, -12, -9, 30, 5, -40, 5, 30, -9, -12, 5, 2, -1}, {0, 0, 0, 15, 220, 1253, 5412, 15642, 44368, 97158, 218816, 410209, 797052, 1350435}, 20]
PROG
(PARI) concat(vector(3), Vec(x^4*(15 + 190*x + 738*x^2 + 1986*x^3 + 1328*x^4 + 2590*x^5 - 242*x^6 + 982*x^7 + 81*x^8 + 12*x^9) / ((1 - x)^8*(1 + x)^6) + O(x^40))) \\ Colin Barker, Jun 27 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jun 26 2017
STATUS
approved