A050402 Number of independent sets of nodes in C_4 X C_n (n > 2).

7, 1, 35, 121, 743, 3561, 18995, 96433, 500871, 2573905, 13292995, 68492073, 353290343, 1821383097, 9392360019, 48428332641, 249716406791, 1287608913057, 6639354593123, 34234612471001, 176524935990503, 910219628918665, 4693389213891699, 24200638961917201

Offset

0,1

Links

Colin Barker, Table of n, a(n) for n = 0..1000

C. Bautista-Ramos and C. Guillen-Galvan, Fibonacci numbers of generalized Zykov sums, J. Integer Seq., 15 (2012), Article 12.7.8

Eric Weisstein's World of Mathematics, Independent Vertex Set

Eric Weisstein's World of Mathematics, Torus Grid Graph

Index entries for linear recurrences with constant coefficients, signature (2,15,8,-7,-2,1).

Formula

a(n) = a(n-1) + 17*a(n-2) + 23*a(n-3) + a(n-4) - 9*a(n-5) - a(n-6) + a(n-7).

G.f.: (7 -13*x -72*x^2 -20*x^3 +17*x^4 +x^5)/((1+x)*(1+2*x-x^2)*(1-5*x-x^2+x^3)). - Colin Barker, Aug 31 2012

Maple

seq(coeff(series((7-13*x-72*x^2-20*x^3+17*x^4+x^5)/((1+x)*(1+2*x-x^2) *(1-5*x-x^2+x^3)), x, n+1), x, n), n = 0 ..30); # G. C. Greubel, Oct 30 2019

Mathematica

CoefficientList[Series[(7 -13*x -72*x^2 -20*x^3 +17*x^4 +x^5)/((1+x)*(1+2*x-x^2)*(1-5*x-x^2+x^3)), {x, 0, 30}], x]

Prog

(PARI) Vec((7-13*x-72*x^2-20*x^3+17*x^4+x^5)/((1+x)*(1+2*x-x^2)*(1-5*x- x^2+x^3)) + O(x^30)) \\ Colin Barker, May 11 2017
(Magma) R<x>:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (7 -13*x -72*x^2 -20*x^3 +17*x^4 +x^5)/((1+x)*(1+2*x-x^2)*(1-5*x-x^2+x^3)) )); // G. C. Greubel, Oct 30 2019
(Sage)
def A050402_list(prec):
    P.<x> = PowerSeriesRing(ZZ, prec)
    return P((7 -13*x -72*x^2 -20*x^3 +17*x^4 +x^5)/((1+x)*(1+2*x-x^2)*(1-5*x-x^2+x^3))).list()
A050402_list(30) # G. C. Greubel, Oct 30 2019
(GAP) a:=[7, 1, 35, 121, 743, 3561];; for n in [7..30] do a[n]:=2*a[n-1] +15*a[n-2]+8*a[n-3]-7*a[n-4]-2*a[n-5]-a[n-6]; od; a; # G. C. Greubel, Oct 30 2019

Crossrefs

Sequence in context: A002678 A147482 A171770 * A027643 A225122 A051931

Adjacent sequences: A050399 A050400 A050401 * A050403 A050404 A050405

Keyword

easy,nonn

Author

Stephen G Penrice, Dec 21 1999

Extensions

More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999

Status

approved