id:A072176 - OEIS Search Results

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Unimodal analogue of Fibonacci numbers: a(n+1)=sum_k A071922(n-k,k).

+0
4

1, 1, 2, 3, 5, 9, 16, 30, 56, 106, 201, 382, 727, 1384, 2636, 5021, 9565, 18222, 34715, 66137, 126001, 240052, 457338, 871304, 1659978, 3162533, 6025150, 11478911, 21869232, 41664520, 79377833, 151227961, 288114394, 548905795 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`Based on the observation that F_{n+1}=sum_k binomial (n-k,k). In both cases the sum is extended to 0<=2k<=n.`
	FORMULA	`G.f.: x(-x^2-x+1)/[(1-x)(1-x-2x^2+x^4)].`
	CROSSREFS	`Cf. A071922, A005578.` `Adjacent sequences: A072173 A072174 A072175 this_sequence A072177 A072178 A072179` `Sequence in context: A050253 A107250 A050168 this_sequence A047061 A136169 A047041`
	KEYWORD	`nonn,easy`
	AUTHOR	`Michele Dondi (bik.mido(AT)tiscalinet.it), Jun 30, 2002`

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Last modified October 7 14:39 EDT 2008. Contains 144666 sequences.

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