This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A002502 Number of connected relations. (Formerly M5336 N2323) 17
 1, 65, 1795, 36317, 636331, 10365005, 162470155, 2495037197, 37898120011, 572284920845, 8614868501515, 129467758660877, 1943971108806091, 29175170378428685, 437752102106036875, 6567275797761209357 (list; graph; refs; listen; history; text; internal format)
 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 polynomes de Bell bidimensionnels et application au denombrement 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 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 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 * A095027 A017781 A017728 Adjacent sequences:  A002499 A002500 A002501 * A002503 A002504 A002505 KEYWORD nonn,nice,easy AUTHOR EXTENSIONS More terms from Goran Kilibarda, Vladeta Jovovic, Apr 14 2004 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.