A258374 Least primitive weird number with n prime divisors, not counting multiplicity.

70, 4030, 4199030, 1550860550

Offset: 3

Author

Robert G. Wilson v, May 28 2015

Keywords

• nonn
• hard
• more

Comments

A proper subset of A002975.

So far all terms are == 2 (mod 4).

From M. F. Hasler, Jul 18 2016: (Start)

a(3) = 2 * 5 * 7 = A002975(1) = A258882(1),

a(4) = 2 * 5 * 13 * 31 = A258401(1) = A258883(1),

a(5) = 2 * 5 * 11 * 59 * 647 = A258884(1),

a(6) = 2 * 5^2 * 29 * 37 * 137 * 211 = A258885(1) = A273815(1). (End)

a(7) <= 4 * 13 * 17 * 449 * 24809 * 228259243 * 11449243661 ≈ 2.6e28, a(8) <= 4 * 13 * 17 * 449 * 24809 * 223842061 * 1123622795959 * 16039588627050434791 ≈ 3.97 e49. - M. F. Hasler, Aug 02 2016

a(7) <= 2 * 5 * 11 * 89 * 167 * 829 * 7972687 ≈ 1.1e16. - M. F. Hasler, Feb 18 2018

Crossrefs

Cf. A002975, A258375.

Programs

Mathematica

(* copy the terms from A002975, assign them equal to 'lst' and then *) Table[ Min@ Select[ lst, PrimeNu@# == n &], {n, 3, 6}]