A359830 Numbers k such that A048675(k) is not a multiple of 3.

2, 3, 4, 5, 7, 9, 10, 11, 12, 13, 16, 17, 18, 19, 21, 22, 23, 24, 25, 28, 29, 30, 31, 32, 34, 37, 39, 40, 41, 42, 43, 45, 46, 47, 49, 52, 53, 54, 55, 56, 57, 59, 60, 61, 62, 66, 67, 70, 71, 72, 73, 75, 76, 78, 79, 80, 81, 82, 83, 85, 87, 88, 89, 91, 94, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 107, 108

Offset: 1

Author

Antti Karttunen, Jan 17 2023

Keywords

• nonn

Comments

Sequence is closed with respect to prime shifting: for any k present in the sequence, also A003961(k) and A348717(k) are present.

Links

• Index entries for sequences computed from indices in prime factorization

Crossrefs

Complement of A332820. Positions of 0's in A353350.

Union of A332821 and A332822.

Cf. A000040 (subsequence), A003961, A048675, A348717, A353348.

Programs

PARI

A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; };
isA359830(n) = !!(A048675(n)%3);

Python

from itertools import count, islice
from sympy import primepi, factorint
def A359830_gen(startvalue=1): # generator of terms >= startvalue
    return filter(lambda n:sum(e<A359830_list = list(islice(A359830_gen(),20)) # Chai Wah Wu, Jan 17 2023