A350961 a(n) = Sum_{k=1..n} 3^Omega(k).

1, 4, 7, 16, 19, 28, 31, 58, 67, 76, 79, 106, 109, 118, 127, 208, 211, 238, 241, 268, 277, 286, 289, 370, 379, 388, 415, 442, 445, 472, 475, 718, 727, 736, 745, 826, 829, 838, 847, 928, 931, 958, 961, 988, 1015, 1024, 1027, 1270, 1279, 1306, 1315, 1342, 1345, 1426, 1435, 1516, 1525, 1534, 1537, 1618

Offset: 1

Author

N. J. A. Sloane, Feb 06 2022

Keywords

• nonn
• easy

References

• Tenenbaum, G. (2015). Introduction to analytic and probabilistic number theory, 3rd ed., American Mathematical Soc. See page 59.

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001222 (Omega), A069205, A069212. Partial sums of A165824.

Programs

Mathematica

Accumulate[3^PrimeOmega[Range[100]]] (* Vaclav Kotesovec, Feb 16 2022 *)

Python

from sympy.ntheory.factor_ import primeomega
def A350961(n): return sum(3**primeomega(m) for m in range(1,n+1)) # Chai Wah Wu, Sep 07 2023