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A002621 Expansion of 1 / ((1-x)^2*(1-x^2)*(1-x^3)*(1-x^4)).
(Formerly M1051 N0394)
+0
3
1, 2, 4, 7, 12, 18, 27, 38, 53, 71, 94, 121, 155, 194, 241, 295, 359, 431, 515, 609, 717, 837, 973, 1123, 1292, 1477, 1683, 1908, 2157, 2427, 2724, 3045, 3396, 3774, 4185, 4626, 5104, 5615, 6166, 6754, 7386, 8058, 8778, 9542, 10358, 11222, 12142, 13114 (list; graph; listen)
OFFSET

0,2

REFERENCES

E. Fix and J. L. Hodges, Jr., Significance probabilities of the Wilcoxon test, Annals Math. Stat., 26 (1955), 301-312.

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=0..1000

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 199

Thomas Wieder, The number of certain k-combinations of an n-set, Applied Mathematics Electronic Notes, vol. 8 (2008).

MAPLE

A002621 := proc(n) local s, x ; s := taylor(1/(1-x)^2, x=0, n+1) ; s := taylor(s/(1-x^2), x=0, n+1) ; s := taylor(s/(1-x^3), x=0, n+1) ; s := taylor(s/(1-x^4), x=0, n+1) ; coeftayl(s, x=0, n) ; end: for n from 0 to 80 do printf("%d, ", A002621(n)) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 06 2007

A002621:=-1/(z**2+1)/(z**2+z+1)/(z+1)**2/(z-1)**5; [S. Plouffe in his 1992 dissertation.]

with(combstruct):ZL:=[st, {st=Prod(left, right), left=Set(U, card=r+2), right=Set(U, card<r), U=Sequence(Z, card>=1)}, unlabeled]: subs(r=2, stack): seq(count(subs(r=2, ZL), size=m), m=4..51) ; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 07 2008

MATHEMATICA

CoefficientList[Series[1/((1-x)^2*(1-x^2)*(1-x^3)*(1-x^4)), {x, 0, 60}], x] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 10 2007

CROSSREFS

Partial sums of A001400.

Sequence in context: A011909 A065962 A049703 this_sequence A033500 A003318 A035300

Adjacent sequences: A002618 A002619 A002620 this_sequence A002622 A002623 A002624

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 06 2007

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.


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