A354163 Index of A354162(n) in A090252.

15, 29, 59, 63, 65, 121, 131, 193, 239, 241, 243, 255, 257, 265, 387, 479, 483, 487, 489, 515, 527, 529, 531, 775, 777, 959, 961, 967, 969, 977, 979, 1023, 1031, 1055, 1059, 1063, 1143, 1551, 1553, 1555, 1921, 1923, 1935, 1937, 1939, 1951, 1953, 1955, 1959, 1961, 2047, 2063, 2064, 2111, 2113, 2119, 2127, 2288, 3073, 3105, 3107, 3111, 3113, 3839

Offset

1,1

Links

Table of n, a(n) for n=1..64.

Prog

(Python)
from itertools import count, islice
from collections import deque
from math import gcd, lcm
from sympy import factorint
def A354163_gen(): # generator of terms
    aset, aqueue, c, b, f, i = {1}, deque([1]), 2, 1, True, 1
    while True:
        for m in count(c):
            if m not in aset and gcd(m, b) == 1:
                i += 1
                if m % 2 and len(fm := factorint(m)) == sum(fm.values()) == 2:
                    yield i
                aset.add(m)
                aqueue.append(m)
                if f: aqueue.popleft()
                b = lcm(*aqueue)
                f = not f
                while c in aset:
                    c += 1
                break
A354163_list = list(islice(A354163_gen(), 25)) # Chai Wah Wu, May 31 2022

Crossrefs

Cf. A090252, A354159, A354160, A354161, A354162.

Sequence in context: A131877 A354161 A211324 * A146427 A202512 A014095

Adjacent sequences: A354160 A354161 A354162 * A354164 A354165 A354166

Keyword

nonn

Author

N. J. A. Sloane, May 30 2022

Status

approved