id:A113021 - OEIS Search Results

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Expansion of x^2/(1-2x+2x^2-x^3-x^4).

+0
2

0, 0, 1, 2, 2, 1, 1, 4, 9, 12, 11, 11, 21, 43, 66, 78, 88, 129, 226, 360, 485, 605, 826, 1287, 2012, 2881, 3851, 5239, 7669, 11592, 16936, 23596, 32581, 46498, 68366, 99913, 142173, 199384, 282701, 408720, 593595, 851835, 1207901, 1714447, 2458522 (list; graph; listen)

	OFFSET	`0,4`
	COMMENT	`Diagonal sums of number triangle A113020.`
	FORMULA	`a(n)=2a(n-1)-2a(n-2)+a(n-3)+a(n-4); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(n-k, j)C(0, j-k)F(j-2k)}}; a(n)=sum{k=0..floor(n/2), (-1)^(k+1)C(n-k, k)F(k)}.`
	CROSSREFS	`Cf. A096750.` `Sequence in context: A132311 A121697 A124976 this_sequence A064552 A123585 A129104` `Adjacent sequences: A113018 A113019 A113020 this_sequence A113022 A113023 A113024`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Oct 11 2005`

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Last modified August 8 13:43 EDT 2008. Contains 142651 sequences.

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