id:A089978 - OEIS Search Results

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Expansion of 1/(1-3x-3x^3).

+0
2

1, 3, 9, 30, 99, 324, 1062, 3483, 11421, 37449, 122796, 402651, 1320300, 4329288, 14195817, 46548351, 152632917, 500486202, 1641103659, 5381209728, 17645087790, 57858574347, 189719352225, 622093320045, 2039855683176 (list; graph; listen)

	OFFSET	`0,2`
	FORMULA	`a(n)=sum{k=0..floor(n/2), C(n-2k, k)3^(n-2k) }`
	CROSSREFS	`Cf. A052912, A000930.` `Sequence in context: A138938 A074003 A078844 this_sequence A052906 A102898 A050181` `Adjacent sequences: A089975 A089976 A089977 this_sequence A089979 A089980 A089981`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Nov 18 2003`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

AT&T Labs Research