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Search: id:A020920
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| A020920 |
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Expansion of 1/(1-4*x)^(9/2). |
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+0
6
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| 1, 18, 198, 1716, 12870, 87516, 554268, 3325608, 19122246, 106234700, 573667380, 3024791640, 15628090140, 79342611480, 396713057400, 1957117749840, 9540949030470, 46021048264620, 219878341708740
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OFFSET
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0,2
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FORMULA
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a(n)=binomial(n+4, 4)*A000984(n+4)/A000984(4), A000984: central binomial coefficients - from Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de)
a(n) = sum( a+b+c+d+e+f+g+h+i=n, f(a)*f(b)*f(c)*f(d)*f(e)*f(f)*f(g)*f(h)*f(i)) with f(n)=A000984(n) . - DELEHAM Philippe (kolotoko(AT)wanadoo.fr), Jan 22 2004
a(n)=A000332(n+4)*A000984(n+4)/70. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 05 2007
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MAPLE
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seq(binomial(2*n, n)*binomial(n, (n-4))/70, n=4..22); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 05 2007
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CROSSREFS
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Sequence in context: A034727 A060532 A073397 this_sequence A083812 A086573 A097515
Adjacent sequences: A020917 A020918 A020919 this_sequence A020921 A020922 A020923
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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