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

0,5

Links

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

Formula

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

Example

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.

Mathematica

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

Prog

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

Crossrefs

Cf. A001222, A102907, A217137.

Sequence in context: A166363 A117470 A070786 * A117500 A297626 A206441

Adjacent sequences: A255539 A255540 A255541 * A255543 A255544 A255545

Keyword

nonn

Author

Zak Seidov, Feb 25 2015

Status

approved