A098037 Number of prime divisors, counted with multiplicity, of the sum of two consecutive primes.

1, 3, 3, 3, 4, 3, 4, 3, 3, 4, 3, 3, 4, 4, 4, 5, 5, 7, 3, 6, 4, 5, 3, 3, 4, 4, 4, 6, 3, 6, 3, 3, 4, 7, 5, 4, 7, 4, 4, 6, 6, 4, 8, 4, 5, 3, 3, 5, 5, 4, 4, 7, 4, 3, 5, 4, 6, 3, 4, 4, 8, 6, 3, 6, 5, 7, 3, 5, 5, 5, 4, 4, 4, 5, 3, 3, 3, 4, 6, 5, 6, 4, 8, 4, 5, 3, 3, 5, 5, 4, 3, 4, 3, 5, 3, 4, 3, 5, 5, 7, 6, 7, 3, 5, 4

Offset

1,2

Comments

Clearly sum of two consecutive primes prime(x) and prime(x+1) has more than 2 prime divisors for all x > 1.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A001222(A001043(n)). - Michel Marcus, Feb 15 2014

Example

Prime(2) + prime(3) = 2*2*2, 3 factors, the second term in the sequence.

Mathematica

PrimeOmega[Total[#]]&/@Partition[Prime[Range[110]], 2, 1] (* Harvey P. Dale, Jun 14 2011 *)

Prog

(PARI) b(n) = for(x=1, n, y1=(prime(x)+prime(x+1)); print1(bigomega(y1)", "))

Crossrefs

Cf. A071215.

Sequence in context: A239963 A084501 A198020 * A079108 A165605 A230194

Adjacent sequences: A098034 A098035 A098036 * A098038 A098039 A098040

Keyword

easy,nonn

Author

Cino Hilliard, Sep 10 2004

Extensions

Definition corrected by Andrew S. Plewe, Apr 08 2007

Status

approved