OFFSET
2,2
LINKS
Eric Weisstein's World of Mathematics, White Bishop Graph
Eric Weisstein's World of Mathematics, Wiener Index
Index entries for linear recurrences with constant coefficients, signature (2,2,-6,0,6,-2,-2,1).
FORMULA
a(n) = (3 + 2*n - 6*n^2 - 8*n^3 + 6*n^4 + 3*(-1)^n*(-1 - 2*n + 2*n^2))/24.
a(n) = 2*a(n-1) + 2*a(n-2) - 6*a(n-3) + 6*a(n-5) - 2*a(n-6) - 2*a(n-7) + a(n-8).
G.f.: x^2*(-1 - 6*x - 24*x^2 - 10*x^3 - 7 x^4)/((-1 + x)^5*(1 + x)^3).
MATHEMATICA
Table[(3 + 2 n - 6 n^2 - 8 n^3 + 6 n^4 + 3 (-1)^n (-1 - 2 n + 2 n^2))/24, {n, 2, 20}]
LinearRecurrence[{2, 2, -6, 0, 6, -2, -2, 1}, {1, 8, 42, 104, 251, 464, 852, 1360}, 20]
CoefficientList[Series[(-1 - 6 x - 24 x^2 - 10 x^3 - 7 x^4)/((-1 + x)^5 (1 + x)^3), {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Sep 08 2017
STATUS
approved