A144946 - OEIS

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A144946

Least a(n) such that p(n)#*(p(n)#+a(n))-1 is prime with p(i)#=i-th primorial.

1, 1, 1, 2, 1, 1, 8, 21, 5, 4, 4, 4, 32, 4, 16, 7, 9, 1, 14, 5, 32, 22, 35, 6, 21, 11, 22, 3, 72, 48, 20, 1, 8, 1, 36, 30, 32, 6, 26, 14, 2, 22, 32, 6, 48, 37, 2, 58, 1, 74 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,4`
	COMMENTS	`As n increases sum(a(i)) for i=1 to n tends to e^gamma/2n(n+1)/2, notice that n*(n+1)/2 is triangular number. [From Pierre CAMI (pierre-cami(AT)bbox.fr), Oct 16 2008]`
	LINKS	`Pierre CAMI, Table of n, a(n) for n = 1..500`
	EXAMPLE	`2(2+1)-1=5 prime so a(1)=1 6(6+1)-1=41 prime so a(2)=1 30*(31)-1=929 prime so a(3)=1.`
	CROSSREFS	`Cf. A144947` `Sequence in context: A167400 A165889 A087127 * A157109 A185814 A174553` `Adjacent sequences: A144943 A144944 A144945 * A144947 A144948 A144949`
	KEYWORD	`nonn`
	AUTHOR	`Pierre CAMI (pierre-cami(AT)bbox.fr), Sep 26 2008, Oct 16 2008`

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Last modified February 14 23:16 EST 2012. Contains 205687 sequences.