A344001 Indices k such that A011772(k) is odd.

1, 2, 4, 6, 8, 14, 15, 16, 20, 22, 24, 28, 30, 32, 33, 38, 40, 45, 46, 51, 52, 54, 60, 62, 63, 64, 65, 66, 69, 72, 77, 86, 87, 90, 91, 92, 94, 95, 96, 102, 112, 115, 116, 118, 120, 123, 124, 126, 128, 130, 134, 138, 140, 141, 142, 143, 144, 145, 148, 152, 153, 154, 156, 158, 159, 161

Offset

1,2

Links

N. J. A. Sloane, Table of n, a(n) for n = 1..7187

Prog

(Python)
from sympy.ntheory.modular import crt
from sympy import factorint
from math import prod
from itertools import count, islice, combinations
def A344001_gen(): # generator of terms
    for n in count(1):
        plist = tuple(p**q for p, q in factorint(2*n).items())
        if len(plist) == 1 or min(min(crt((m, 2*n//m), (0, -1))[0], crt((2*n//m, m), (0, -1))[0]) for m in (prod(d) for l in range(1, len(plist)//2+1) for d in combinations(plist, l))) & 1:
            yield n
A344001_list = list(islice(A344001_gen(), 40)) # Chai Wah Wu, Jun 15 2022

Crossrefs

Cf. A011772, A343999 (characteristic function), A344000 (complement).

Cf. also A354919.

Sequence in context: A086526 A086529 A054409 * A152973 A089747 A274170

Adjacent sequences: A343998 A343999 A344000 * A344002 A344003 A344004

Keyword

nonn

Author

N. J. A. Sloane, Jun 01 2021

Status

approved