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Search: id:A000478
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| A000478 |
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Number of ways of placing n labeled balls into 3 indistinguishable boxes with at least 2 balls in each box.
(Formerly M4978 N2138)
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+0
4
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| 15, 105, 490, 1918, 6825, 22935, 74316, 235092, 731731, 2252341, 6879678, 20900922, 63259533, 190957923, 575363776, 1731333808, 5205011031, 15638101281, 46962537810, 140988276150, 423174543025, 1269959836015
(list; graph; listen)
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OFFSET
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6,1
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COMMENT
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Associated Stirling numbers.
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REFERENCES
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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.
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 222.
F. N. David and D. E. Barton, Combinatorial Chance. Hafner, NY, 1962, p. 296.
J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 76.
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LINKS
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T. D. Noe, Table of n, a(n) for n=6..200
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.
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FORMULA
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E.g.f.: ((exp(x) - 1 - x)^3)/3!. G.f.: x^6*(12*x^3 - 40*x^2 + 45*x - 15)/((1 - x)^3*(1 - 2*x)^2*(3*x - 1))
a(n) = (1+n+n^2)/2 - (1/2 + n/4)*2^n + 3^n/6 - Michael Steyer (m.steyer(AT)osram.de), Jan 09 2005
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EXAMPLE
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a(6)=6!/(2!*2!*2!*3!)=15
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MAPLE
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A000478:=-(-15+45*z-40*z**2+12*z**3)/(-1+3*z)/(2*z-1)**2/(z-1)**3; [Conjectured by S. Plouffe in his 1992 dissertation.]
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CROSSREFS
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Cf. A000247 (2 boxes), A058844 (4 boxes).
Sequence in context: A076767 A022610 A006857 this_sequence A055848 A058085 A060218
Adjacent sequences: A000475 A000476 A000477 this_sequence A000479 A000480 A000481
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KEYWORD
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nonn,easy,nice
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AUTHOR
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njas
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EXTENSIONS
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Additional comments from Michael Steyer (msteyer(AT)osram.de), Dec 02 2000. More terms from James A. Sellers (sellersj(AT)math.psu.edu), Dec 06 2000
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