login
A354163
Index of A354162(n) in A090252.
3
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
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
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, May 30 2022
STATUS
approved