id:A135715 - OEIS Search Results

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Number of primes of the form p(n)#/p(k) + 1, where 1 <= k <= n.

+0
3

1, 1, 2, 3, 3, 3, 3, 2, 2, 3, 4, 5, 2, 1, 3, 2, 3, 1, 0, 1, 1, 4, 5, 0, 0, 2, 1, 1, 3, 2, 1, 3, 0, 3, 1, 1, 2, 2, 6, 2, 4, 1, 4, 4, 3, 4, 3, 2, 4, 1, 0, 3, 3, 3, 4, 2, 2, 1, 3, 1, 2, 1, 4, 1, 2, 1, 2, 3, 3, 1, 3, 2, 2, 2, 4, 4, 2, 2, 0, 1, 3, 1, 1, 3, 1, 1, 0, 1, 0, 4, 1, 1, 4, 1, 1, 1, 2, 4, 1, 1, 2, 2, 3, 7, 3 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`p(k) is k-th prime; p(n)# is n-th primorial, A002110(n). For the larger n, these are only counts of highly probable primes. Of the first 500 terms, the maximum occurs once, a(172)=8; the mode is 2, occurring 135 times.`
	LINKS	`Rick L. Shepherd, Table of n, a(n) for n = 1..500`
	EXAMPLE	`a(3)=2 because p(3)#=A002110(3)=30 and 30/3+1=11 and 30/5+1=7 are both prime and there are no other primes of this form.`
	PROGRAM	`(PARI) a(n)= p=prod(k=1, n, prime(k)); sum(k=1, n, isprime(p/prime(k)+1))`
	CROSSREFS	`Cf. A135714, A135716, A002110.` `Sequence in context: A097032 A127661 A008968 this_sequence A089326 A022923 A158799` `Adjacent sequences: A135712 A135713 A135714 this_sequence A135716 A135717 A135718`
	KEYWORD	`nonn`
	AUTHOR	`Rick L. Shepherd (rshepherd2(AT)hotmail.com), Nov 30 2007`

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

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