id:A130249 - OEIS Search Results

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Maximal index k of a Jacobsthal number such that A001045(k)<=n (the 'lower' Jacobsthal inverse).

+0
11

0, 2, 2, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`Inverse of the Jacobsthal sequence (A001045), nearly, since a(A001045(n))=n except for n=1 (see A130250 for another version). a(n)+1 is equal to the partial sum of the Jacobsthal indicator sequence (see A105348).`
	FORMULA	`a(n)=floor(log_2(3n+1)). Also true: a(n)=A130250(n+1)-1=A130253(n)-1. G.f.: g(x)=1/(1-x)*sum{k>=1, x^A001045(k)}.`
	EXAMPLE	`a(12)=5, since A001045(5)=11<=12, but A001045(6)=21>12.`
	CROSSREFS	`For partial sums see A130251. Other related sequences A130250, A130253, A105348. A001045, A130233, A130241.` `Sequence in context: A074719 A079730 A035486 this_sequence A061071 A122258 A068509` `Adjacent sequences: A130246 A130247 A130248 this_sequence A130250 A130251 A130252`
	KEYWORD	`nonn`
	AUTHOR	`Hieronymus Fischer (Hieronymus.Fischer(AT)gmx.de), May 20 2007`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

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