A355139 The indices where A355061(n) = 6.

3, 7, 11, 19, 46, 75, 113, 138, 169, 186, 227, 240, 287, 374, 382, 481, 528, 536, 672, 713, 722, 760, 836, 922, 972, 1015, 1031, 1052, 1077, 1122, 1144, 1235, 1244, 1371, 1392, 1466, 1549, 1613, 1669, 1859, 1938, 2059, 2109, 2118, 2127, 2391, 2557, 2661, 2730, 2739, 2765, 2798, 2949, 2962

Offset: 1

Author

Scott R. Shannon, Jun 20 2022

Keywords

• nonn

Comments

See A355061 for further details.

Crossrefs

Cf. A355061, A355138.

Programs

Python

from sympy import primefactors
from itertools import count, islice
def agen(): # generator of terms
    an1, an, f1, f, pset = 2, 6, {2}, {2, 3}, {2, 12}
    for n in count(4):
        if an == 6: yield n-1
        an2, an1, an, f2, f1 = an1, an, 6, f1, f
        f = set(primefactors(an))
        while an*an1 in pset or f1&f == set() or f2&f != set() or f <= f1:
            an += 1; f = set(primefactors(an))
        pset.add(an*an1)
print(list(islice(agen(), 54))) # Michael S. Branicky, Jun 20 2022