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A094735
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Number of connected 3-element multiantichains on a labeled n-set.
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1
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0, 1, 1, 8, 75, 796, 8051, 73788, 623155, 4965836, 38028051, 283400668, 2072874035, 14966280876, 107083717651, 761327161148, 5388524417715, 38017832427916, 267623218488851, 1880883687651228, 13203904989574195, 92616374066478956, 649261556308773651
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OFFSET
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0,4
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LINKS
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FORMULA
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E.g.f.: (1/3!)*(exp(7*x) - 6*exp(5*x) + 3*exp(4*x) + 20*exp(3*x) - 39*exp(2*x) + 35*exp(x) - 14).
G.f.: -x*(1960*x^5 - 1695*x^4 + 731*x^3 - 176*x^2 + 21*x - 1) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)*(7*x-1)). - Colin Barker, Jul 13 2013
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MATHEMATICA
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Table[(7^n-6*5^n+20*3^n+3*4^n-39*2^n+35)/6(1-UnitStep[-n]), {n, 0, 20}] (* Benedict W. J. Irwin, May 25 2016 *)
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PROG
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(PARI) x='x+O('x^50); concat([0], Vec(serlaplace((1/3!)*(exp(7*x) - 6*exp(5*x) + 3*exp(4*x) + 20*exp(3*x) - 39*exp(2*x) + 35*exp(x) - 14)))) \\ G. C. Greubel, Oct 08 2017
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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