A002502 Number of connected relations. (Formerly M5336 N2323)

1, 65, 1795, 36317, 636331, 10365005, 162470155, 2495037197, 37898120011, 572284920845, 8614868501515, 129467758660877, 1943971108806091, 29175170378428685, 437752102106036875, 6567275797761209357, 98517076408654506571, 1477819563125542784525, 22167800138932050900235

Offset

1,2

References

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

T. D. Noe, Table of n, a(n) for n=1..100

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 (38,-539,3622,-11640,14400).

Formula

a(n) = 15^n-4*8^n-3*6^n+12*5^n-6*4^n. - Goran Kilibarda, Vladeta Jovovic, Apr 14 2004

G.f.: x*(-1-27*x+136*x^2+480*x^3)/((6*x-1)*(5*x-1)*(15*x-1)*(4*x-1)*(8*x-1)). - R. J. Mathar, Jun 09 2013

E.g.f.: exp(4*x)*(exp(11*x) - 4*exp(4*x) - 3*exp(2*x) + 12*exp(x) - 6). - Stefano Spezia, Jun 02 2026

Mathematica

LinearRecurrence[{38, -539, 3622, -11640, 14400}, {1, 65, 1795, 36317, 636331}, 20] (* Harvey P. Dale, Mar 24 2017 *)

Crossrefs

Cf. A005333, A001047, A002501, A093732, A093733.

A diagonal of A262307.

Sequence in context: A183271 A197088 A031604 * A333118 A095027 A017781

Adjacent sequences: A002499 A002500 A002501 * A002503 A002504 A002505

Keyword

nonn,nice,easy,changed

Author

N. J. A. Sloane

Extensions

More terms from Goran Kilibarda, Vladeta Jovovic, Apr 14 2004

Status

approved