A056160 Sum of A054988 and A054989.

1, 2, 2, 3, 2, 3, 5, 5, 5, 5, 3, 7, 4, 4, 6, 7, 6, 5, 5, 6, 4, 7, 5, 5, 5, 4, 8, 8, 7, 6, 8, 6, 9, 5, 6, 6, 9, 8, 9, 5, 11, 7, 9, 7, 9, 10, 11, 4, 9, 6, 7, 7, 7, 6, 8, 9, 8, 12, 7, 8, 8, 9, 7, 6, 8, 6, 9, 4, 8, 7, 12, 10, 7, 8, 7, 7, 10, 8, 9, 7, 9

Offset

1,2

Comments

Prime divisors are counted with multiplicity.

If "2" were a cluster point of this sequence it would follow that there are infinitely many twin primes.

Links

Table of n, a(n) for n=1..81.

Prog

(PARI) a(n) = my(P=prod(k=1, n, prime(k))); bigomega(P+1) + bigomega(P-1); \\ Michel Marcus, Mar 07 2022

Crossrefs

Cf. A054988, A054989.

Sequence in context: A164738 A126225 A306997 * A106245 A129568 A177892

Adjacent sequences: A056157 A056158 A056159 * A056161 A056162 A056163

Keyword

hard,nonn

Author

Arne Ring (arne.ring(AT)epost.de), Aug 01 2000

Extensions

a(36)-a(81) from Charles R Greathouse IV, May 07 2011

Status

approved