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A024419
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a(n) = n!(1/C(n,0) + 1/C(n,1) + ... + 1/C(n,[ n/2 ])).
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2
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1, 1, 3, 8, 34, 156, 924, 6144, 48096, 420480, 4134240, 44720640, 530444160, 6824805120, 94787884800, 1412038656000, 22464536371200, 380017225728000, 6811416338227200, 128936055177216000, 2570286167543808000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| G.f.: (G(x)^2+H(x))/2 where G(x) = Sum_{k>=0} k!*x^k and G(x) = Sum_{k>=0} k!^2*x^(2*k). - Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 22 2007
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EXAMPLE
| a(3)=3!*(1/1 + 1/3)=6*4/3=8
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MAPLE
| a:=proc(n) options operator, arrow: factorial(n)*(sum(1/binomial(n, k), k= 0.. floor((1/2)*n))) end proc: seq(a(n), n=0..21); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Oct 11 2007
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CROSSREFS
| Sequence in context: A184255 A001120 A117722 * A186517 A094448 A063805
Adjacent sequences: A024416 A024417 A024418 * A024420 A024421 A024422
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KEYWORD
| nonn,easy
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Oct 11 2007
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