A093732 Number of connected relations.

1, 211, 14221, 636331, 23679901, 805351531, 26175881341, 831358677451, 26094426008221, 814105545191851, 25320182311228861, 786251347986776971, 24394981288950302941, 756583120577782494571, 23459491617092461686781, 727330825918603925122891

Offset

1,2

Links

T. D. Noe, Table of n, a(n) for n = 1..200

G. Kilibarda and V. Jovovic, Enumeration of some classes of T_0-hypergraphs, arXiv:1411.4187 [math.CO], 2014.

G. Kreweras, Inversion des polynômes de Bell bidimensionnels et application au dénombrement des relations binaires connexes, C. R. Acad. Sci. Paris Ser. A-B 268 1969 A577-A579.

Index entries for linear recurrences with constant coefficients, signature (84,-2774,47548,-462525,2575088,-7643820,9374400).

Formula

a(n) = 31^n - 5*16^n - 10*10^n + 20*9^n + 30*7^n - 60*6^n + 24*5^n.

G.f.: -x*(1+127*x-729*x^2-20467*x^3+107048*x^4+259620*x^5) / ( (9*x-1)*(6*x-1)*(7*x-1)*(5*x-1)*(31*x-1)*(10*x-1)*(16*x-1) ). - R. J. Mathar, Jun 09 2013

Mathematica

Table[31^n - 5*16^n - 10*10^n + 20*9^n + 30*7^n - 60*6^n + 24*5^n, {n, 25}] (* T. D. Noe, May 29 2012 *)

Prog

(PARI) a(n)=31^n-5*16^n-10*10^n+20*9^n+30*7^n-60*6^n+24*5^n \\ Charles R Greathouse IV, Jun 16 2015

Crossrefs

Cf. A005333, A001047, A002501, A002502, A093733.

Sequence in context: A212851 A069425 A276461 * A116075 A276462 A096834

Adjacent sequences: A093729 A093730 A093731 * A093733 A093734 A093735

Keyword

nonn,easy

Author

Goran Kilibarda, Vladeta Jovovic, Apr 14 2004

Status

approved