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 A296200 Harary index of the n X n white bishop graph. 0
 1, 5, 21, 47, 104, 182, 318, 490, 755, 1075, 1531, 2065, 2786, 3612, 4684, 5892, 7413, 9105, 11185, 13475, 16236, 19250, 22826, 26702, 31239, 36127, 41783, 47845, 54790, 62200, 70616, 79560, 89641, 100317, 112269, 124887, 138928, 153710, 170070, 187250 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 LINKS Eric Weisstein's World of Mathematics, Harary Index Eric Weisstein's World of Mathematics, White Bishop Graph Index entries for linear recurrences with constant coefficients, signature (2, 2, -6, 0, 6, -2, -2, 1). FORMULA a(n) = (21 - 4*n - 42*n^2 + 16*n^3 + 6*n^4 + 3*(-1)^n*(-7 + 4*n + 2*n^2))/96. 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 - 3*x - 9*x^2 - x^3 + 2*x^4)/((-1 + x)^5*(1 + x)^3). MATHEMATICA Table[(21 - 4 n - 42 n^2 + 16 n^3 + 6 n^4 + 3 (-1)^n (-7 + 4 n + 2 n^2))/96, {n, 20}] LinearRecurrence[{2, 2, -6, 0, 6, -2, -2, 1}, {1, 5, 21, 47, 104, 182, 318, 490}, 20] CoefficientList[Series[(-1 - 3 x - 9 x^2 - x^3 + 2 x^4)/((-1 + x)^5 (1 + x)^3), {x, 0, 20}], x] PROG (PARI) first(n) = Vec(x^2*(-1 - 3*x - 9*x^2 - x^3 + 2*x^4)/((-1 + x)^5*(1 + x)^3) + O(x^(n+2))) \\ Iain Fox, Dec 07 2017 CROSSREFS Sequence in context: A049741 A166010 A146846 * A041825 A022268 A201279 Adjacent sequences:  A296197 A296198 A296199 * A296201 A296202 A296203 KEYWORD nonn,easy AUTHOR Eric W. Weisstein, Dec 07 2017 STATUS approved

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Last modified January 17 23:37 EST 2020. Contains 330995 sequences. (Running on oeis4.)