id:A157004 - OEIS Search Results

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Transform of central binomial coefficients A000984 whose Hankel transform obeys a Somos-4 recurrence.

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1, 2, 6, 18, 58, 192, 650, 2232, 7746, 27096, 95376, 337404, 1198546, 4272308, 15273888, 54744268, 196646922, 707747988, 2551624304, 9213416524, 33313656888, 120604436624, 437112790668, 1585877246424, 5759085911154 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`Hankel transform is A157005. Image of A000984 under Riordan array (1,x(1-x^2)).`
	FORMULA	`G.f.: 1/sqrt(1-4x(1-x^2));` `a(n)=sum{k=0..n, (-1)^((n-k)/2)(1+(-1)^(n-k))C(k,floor((n-k)/2))*A000984(k)/2}.`
	CROSSREFS	`Cf. A157003.` `Sequence in context: A081057 A000137 A151282 this_sequence A085139 A150041 A150042` `Adjacent sequences: A157001 A157002 A157003 this_sequence A157005 A157006 A157007`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Feb 20 2009`

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

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