A102298 Number of prime divisors with multiplicity of n+1 where n and n+1 are composite or twin composite numbers.

2, 2, 2, 4, 2, 2, 2, 2, 3, 3, 2, 2, 2, 4, 2, 4, 3, 2, 2, 3, 2, 3, 2, 4, 2, 2, 3, 6, 2, 3, 2, 3, 3, 3, 2, 3, 4, 2, 2, 2, 2, 4, 2, 3, 2, 2, 2, 6, 3, 4, 3, 2, 2, 5, 2, 3, 3, 2, 2, 5, 2, 2, 2, 3, 3, 4, 2, 3, 2, 2, 4, 4, 2, 2, 2, 6, 2, 2, 3, 3, 3, 3, 2, 4, 2, 6, 2, 5, 3, 2, 2, 3, 3, 3, 3, 5, 2, 2, 2, 4, 2, 3, 2, 3, 4

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

For n=8 n+1 = 9 = 3*3 or 2 prime divisors with multiplicity.

Mathematica

PrimeOmega[#[[2]]]&/@Select[Partition[Range[300], 2, 1], And@@ CompositeQ[ #]&] (* Harvey P. Dale, Jun 09 2016 *)

Prog

(PARI) f(n) = for(x=1, n, y=composite(x)+1; if(!isprime(y), print1(bigomega(y)", "))) composite(n) =\The n-th composite number. 1 is def as not prime nor composite. { local(c, x); c=1; x=1; while(c <= n, x++; if(!isprime(x), c++); ); return(x) }

Crossrefs

Sequence in context: A111735 A211454 A242310 * A049298 A075016 A279409

Adjacent sequences: A102295 A102296 A102297 * A102299 A102300 A102301

Keyword

easy,nonn

Author

Cino Hilliard, Feb 19 2005

Status

approved