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A020920
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Expansion of 1/(1-4*x)^(9/2).
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7
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1, 18, 198, 1716, 12870, 87516, 554268, 3325608, 19122246, 106234700, 573667380, 3024791640, 15628090140, 79342611480, 396713057400, 1957117749840, 9540949030470, 46021048264620, 219878341708740
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Also convolution of A000984 with A038846, also convolution of A000302 with A020918, also convolution of A002457 with A038845, also convolution of A002697 with A002802. [From Rui Duarte, Oct 08 2011]
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FORMULA
| 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
a(n) = ((2n+7)(2n+5)(2n+3)(2n+1)/(7*5*3*1)) * binomial(2n, n), a(n) = binomial(2n+8, 8) * binomial(2n, n) / binomial(n+4, 4), a(n) = binomial(n+4, 4) * binomial(2n+8, n+4) / binomial(8, 4) [From Rui Duarte, Oct 08 2011]
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MAPLE
| 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
| Sequence in context: A034727 A060532 A073397 * A083812 A086573 A097515
Adjacent sequences: A020917 A020918 A020919 * A020921 A020922 A020923
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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