A354791 Indices of nonprime terms in A354790.

1, 7, 14, 15, 17, 29, 31, 35, 59, 63, 64, 71, 79, 119, 120, 127, 129, 143, 159, 223, 239, 241, 255, 259, 260, 287, 288, 319, 320, 447, 479, 483, 484, 511, 512, 519, 521, 575, 577, 639, 641, 895, 959, 960, 967, 968, 969, 1023, 1025, 1039, 1043, 1044, 1151, 1152

Offset

1,2

Links

Rémy Sigrist, Table of n, a(n) for n = 1..5715

Rémy Sigrist, C program

Prog

(Python)
from math import lcm, gcd
from itertools import count, islice
from collections import deque
from sympy import factorint
def A354791_gen(): # generator of terms
    aset, aqueue, c, b, f, i = {1}, deque([1]), 2, 1, True, 1
    yield 1
    while True:
        for m in count(c):
            if m not in aset and gcd(m, b) == 1 and all(map(lambda n:n<=1, fs:=factorint(m).values())):
                i += 1
                if len(fs) > 1:
                    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
A354791_list = list(islice(A354791_gen(), 30)) # Chai Wah Wu, Jul 17 2022
(C) See Links section.

Crossrefs

Cf. A354790, A354792.

Sequence in context: A232877 A232860 A232797 * A107976 A022557 A307546

Adjacent sequences: A354788 A354789 A354790 * A354792 A354793 A354794

Keyword

nonn

Author

Michael De Vlieger and N. J. A. Sloane, Jul 17 2022

Extensions

More terms from Rémy Sigrist, Jul 17 2022

Status

approved