A351499 Odd m in A352928.

1, 9, 15, 75, 105, 315, 525, 735, 945, 1155, 1365, 1575, 1995, 3465, 4305, 5775, 6615, 7035, 8085, 8925, 9765, 10395, 11235, 12495, 12705, 13545, 15015, 19635, 26565, 28875, 31185, 33495, 38115, 45045, 255255, 405405, 525525, 765765, 975975, 1036035, 1786785, 2297295

Offset: 1

Author

Michael De Vlieger, May 03 2022

Keywords

• nonn

Crossrefs

Cf. A093714, A351498, A352928.

Programs

Mathematica

nn = 2^20; c = {1}; j = 1; s = 0; u = 1; {1}~Join~Reap[Do[k = u; While[Nand[FreeQ[c, k], CoprimeQ[j, k], k != j + 1], k++]; j = k; AppendTo[c, k]; If[k == u, If[OddQ[u], Sow[u]]; While[MemberQ[c, u], u++]; c = DeleteCases[c, _?(# < u &)]], {i, 2, nn}]][[-1, -1]]

Python

from math import gcd
from itertools import islice
def agen(): # generator of terms
    an, aset, mink, seen = 1, {1}, 2, {1}
    yield 1
    while True:
        if mink%2 and mink not in seen: yield mink; seen.add(mink)
        k = mink
        while k in aset or gcd(an, k) != 1 or k-an == 1: k += 1
        an = k; aset.add(an)
        while mink in aset: mink += 1
print(list(islice(agen(), 42))) # Michael S. Branicky, May 03 2022