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Search: id:A141222
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| A141222 |
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Expansion of (sqrt(1-4x)*(1-4x+4x^2)-16x^2+8x-1)/(2x*(1-4x^2)). |
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+0
3
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| 1, 5, 22, 95, 406, 1722, 7260, 30459, 127270, 529958, 2200276, 9111830, 37650172, 155266100, 639191160, 2627302995, 10784089350, 44208873390, 181025067300, 740483276610, 3026059513620, 12355464845100
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Apply Riordan array (1/sqrt(1-4x), xc(x)) to A131056, c(x) the g.f. of A000108.
Apply Riordan array (c(x)/sqrt(1-4*x),x*c(x)^2) to A131055.
Hankel transform appears to be (-1)^n*A085046(n).
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FORMULA
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a(n)=sum{k=0..n, (1+(k+1)2^(k-1)-0^k/2)*C(2n-k,n-k)}; a(n)=sum{k=0..n, C(2n,k)*C(n+1,2n-k)};
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CROSSREFS
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Sequence in context: A128746 A049675 A053154 this_sequence A127360 A116415 A026861
Adjacent sequences: A141219 A141220 A141221 this_sequence A141223 A141224 A141225
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jun 14 2008
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