A093732 Number of connected relations.

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

Offset: 1

Author

Goran Kilibarda, Vladeta Jovovic, Apr 14 2004

Keywords

• nonn
• easy

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).

Crossrefs

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

Programs

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 *)

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

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