id:A123341 - OEIS Search Results

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a(1) = 1, a(n) = Sum_{k=1}^{Pi(n)} a(n-k) for n > 1, where Pi(n) is the number of primes less than or equal to n.

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1, 1, 2, 3, 6, 11, 22, 42, 81, 156, 312, 613, 1226, 2430, 4818, 9555, 19110, 38064, 76128, 151944, 303275, 605324, 1210648, 2418866, 4832914, 9656273, 19293436, 38548808, 77097616, 154119104, 308238208, 616324472, 1232345669, 2464086014 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`Conjecture: lim_{n->infinity} a(n)/2^n > 0; appears to be about 0.1432645404.`
	FORMULA	`a(1) = a(2) = 1, for p an odd prime, a(p) = 2a(p-1), otherwise a(n) = 2a(n-1) - a(n - pi(n) - 1).`
	CROSSREFS	`Cf: A000720, A000045, A001590.` `Sequence in context: A082616 A018613 A036589 this_sequence A141072 A043328 A002083` `Adjacent sequences: A123338 A123339 A123340 this_sequence A123342 A123343 A123344`
	KEYWORD	`nonn`
	AUTHOR	`Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Oct 11 2006`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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