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
Keywords
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)
Programs
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Mathematica
a[n_]:= PrimeOmega[3^n+10];
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PARI
a(n) = bigomega(3^n+10);
Formula
a(n) = A001222(3^n+10).