A334118 Primitive terms of A334117: odd numbers m such that sigma(m, -1) >= 3/2 with no proper divisors sharing this property.

15, 21, 99, 117, 153, 171, 207, 429, 561, 627, 663, 741, 759, 783, 837, 957, 999, 1023, 1107, 1161, 1269, 1431, 1593, 1647, 1809, 1917, 1925, 1971, 2133, 2275, 2695, 2975, 3185, 4235, 5005, 6545, 6723, 7209, 7315, 7735, 7857, 8091, 8181, 8343, 8645, 8667, 8829, 8855

Offset: 1

Author

Charles R Greathouse IV, Apr 14 2020

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A334117, A000203, A005231, A119240.

Programs

Mathematica

Select[Range[1, 10^4, 2], DivisorSigma[-1, #] >= 3/2 && Max[DivisorSigma[-1, Most[Divisors[#]]]] < 3/2 &] (* Amiram Eldar, Dec 28 2024 *)

PARI

list(lim)=my(v=List(), k); forfactored(n=15,lim\1, if(sigma(n,-1)>=3/2 && (k=n[1])%2, for(i=1,#v, if(k%v[i]==0, next(2))); listput(v,k))); Vec(v)