A354161 Index of A354160(n) in A090252.

15, 29, 47, 59, 63, 65, 121, 131, 193, 239, 241, 243, 255, 257, 265, 387, 479, 483, 487, 489, 515, 527, 529, 531, 767, 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, 3071, 3073, 3105, 3107

Offset: 1

Author

N. J. A. Sloane, May 30 2022

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..2517

Crossrefs

Cf. A090252, A354159, A354160, A354162, A354163.

Programs

Python

from itertools import count, islice
from collections import deque
from math import gcd, lcm
from sympy import factorint
def A354161_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 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
A354161_list = list(islice(A354161_gen(),25)) # Chai Wah Wu, May 31 2022