id:A139789 - OEIS Search Results

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Numbers of primes < nth-prime such that prime(n) + 4 is prime.

+0
2

0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 19, 19, 19, 19, 19, 20, 20, 20, 20, 20, 21, 21, 21 (list; graph; listen)

	OFFSET	`1,5`
	MAPLE	`A139789 := proc(n) local a, i; a := 0 ; for i from 1 to n-1 do if isprime(ithprime(i)+4) then a :=a +1 ; fi; od: a ; end: for n from 1 to 100 do printf("%d, ", A139789(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 05 2008]`
	CROSSREFS	`Cf. A082462.` `Sequence in context: A123087 A071868 A082447 this_sequence A000720 A070549 A074796` `Adjacent sequences: A139786 A139787 A139788 this_sequence A139790 A139791 A139792`
	KEYWORD	`nonn`
	AUTHOR	`Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), May 21 2008`
	EXTENSIONS	`0 added in front, some 6's added and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 05 2008`

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Last modified November 25 08:46 EST 2009. Contains 167481 sequences.

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