id:A088627 - OEIS Search Results

Search: id:A088627

Displaying 1-1 of 1 results found.

page 1

Let 2n = r*s. Then a(n) = number of primes of the form r+s (r= 1 and s = 2n contributes 1 to the count if 2n+1 is prime).

+0
2

1, 1, 2, 0, 2, 2, 0, 1, 2, 0, 2, 1, 0, 2, 4, 0, 1, 2, 0, 2, 4, 0, 1, 1, 0, 2, 1, 0, 2, 4, 0, 0, 2, 0, 4, 2, 0, 1, 4, 0, 2, 2, 0, 2, 3, 0, 0, 1, 0, 2, 4, 0, 1, 2, 0, 2, 2, 0, 1, 3, 0, 0, 2, 0, 4, 3, 0, 1, 3, 0, 1, 0, 0, 2, 3, 0, 2, 2, 0, 1, 2, 0, 1, 3, 0, 2, 2, 0, 1, 3, 0, 1, 1, 0, 4, 2, 0, 2, 4, 0, 1, 2, 0, 1, 8 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`Only even numbers yield primes hence odd numbers are not considered.` `There is an upper bound: if n has only k different prime divisors > 2, then a(n) <= 2^k. - Matthias Engelhardt (Matthias.R.Engelhardt(AT)web.de), Jan 05 2004`
	LINKS	`M. Engelhardt, Number of Primes arising as Sum of a Factorization.`
	EXAMPLE	`a(9) = 2 18 = 118, 1+18= 19 and 18 = 29, 2+9 = 11, two primes arise.`
	CROSSREFS	`Cf. A091350.` `Sequence in context: A028928 A091379 A106277 this_sequence A024713 A123530 A123063` `Adjacent sequences: A088624 A088625 A088626 this_sequence A088628 A088629 A088630`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 19 2003`
	EXTENSIONS	`More terms from Matthias Engelhardt (Matthias.R.Engelhardt(AT)web.de), Jan 05 2004` `More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Aug 15 2005`

page 1

Search completed in 0.002 seconds

Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

AT&T Labs Research