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A005387 Number of partitional matroids on n elements.
(Formerly M1493)
1
1, 2, 5, 16, 62, 276, 1377, 7596, 45789, 298626, 2090910, 15621640, 123897413, 1038535174, 9165475893, 84886111212, 822648571314, 8321077557124, 87648445601429, 959450073912136, 10894692556576613, 128114221270929646 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

Recski, A.; Enumerating partitional matroids. Stud. Sci. Math. Hungar. 9 (1974), 247-249 (1975).

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=0..100

Index entries for sequences related to matroids

FORMULA

E.g.f.: exp ((x-1)*e^x + 2*x + 1 ).

MATHEMATICA

With[{nn=30}, CoefficientList[Series[Exp[(x-1)E^x+2x+1], {x, 0, nn}], x]Range[0, nn]!] (* Harvey P. Dale, Nov 22 2012 *)

CROSSREFS

Sequence in context: A033543 A124531 A129578 * A173469 A138549 A210667

Adjacent sequences:  A005384 A005385 A005386 * A005388 A005389 A005390

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from James A. Sellers, Aug 21 2000

STATUS

approved

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Last modified November 27 14:16 EST 2014. Contains 250210 sequences.