A255542 a(n) = number of prime factors of (3^n + 10) counted with multiplicity.

1, 1, 1, 1, 2, 2, 1, 3, 1, 2, 4, 3, 2, 3, 2, 3, 5, 3, 1, 3, 3, 3, 4, 2, 3, 4, 2, 6, 4, 3, 3, 4, 3, 2, 5, 4, 1, 4, 5, 5, 5, 2, 4, 3, 3, 5, 5, 2, 2, 5, 4, 3, 4, 3, 3, 6, 4, 4, 5, 5, 7, 3, 3, 4, 5, 5, 2, 6, 3, 5, 5, 4, 4, 5, 3, 7, 6, 4, 4, 3, 2, 4, 5, 4, 2, 4, 3, 2, 4, 4, 4, 5, 4, 6, 7, 4, 3, 5, 1, 4

Offset: 0

Author

Zak Seidov, Feb 25 2015

Keywords

• nonn

Examples

			a(0) = 1 because 3^0+10 = 11 is prime.
a(4) = 2 because 3^4+10 = 91 = 7*13 is semiprime.
a(7) = 3 because 3^7+10 = 2197 = 13*13*13 is 3-almost prime.
a(10) = 4 because 3^7+10 = 59059 = 7*11*13*59 is 4-almost prime.
a(16) = 5 because 3^16+10 = 43046731 = 7*13*23*131*157 is 5-almost prime.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 0..257 (terms 0..151 from Zak Seidov)

Crossrefs

Cf. A001222, A102907, A217137.

Programs

Mathematica

a[n_]:= PrimeOmega[3^n+10];

PARI

a(n) = bigomega(3^n+10);

Formula

a(n) = A001222(3^n+10).