A354764 Squarefree kernel of A090252(n) (cf. A007947).

1, 2, 3, 5, 2, 7, 3, 11, 13, 17, 2, 19, 23, 5, 21, 29, 31, 37, 41, 43, 47, 53, 2, 59, 61, 67, 71, 73, 55, 79, 3, 7, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 26, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 85, 11, 223, 227, 57, 229, 161, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281

Offset

1,2

Links

Table of n, a(n) for n=1..75.

Prog

(Python)
from itertools import count, islice
from math import prod, gcd, lcm
from collections import deque
from sympy import primefactors
def A354764_gen(): # generator of terms
    aset, aqueue, c, b, f = {1}, deque([1]), 2, 1, True
    yield 1
    while True:
        for m in count(c):
            if m not in aset and gcd(m, b) == 1:
                yield prod(primefactors(m))
                aset.add(m)
                aqueue.append(m)
                if f: aqueue.popleft()
                b = lcm(*aqueue)
                f = not f
                while c in aset:
                    c += 1
                break
A354764_list = list(islice(A354764_gen(), 20)) # Chai Wah Wu, Jun 18 2022

Crossrefs

Cf. A007947, A090252.

Sequence in context: A175723 A084346 A165911 * A096062 A176195 A231233

Adjacent sequences: A354761 A354762 A354763 * A354765 A354766 A354767

Keyword

nonn

Author

N. J. A. Sloane, Jun 18 2022

Status

approved