A111398 Numbers which are the cube roots of the product of their proper divisors.

1, 24, 30, 40, 42, 54, 56, 66, 70, 78, 88, 102, 104, 105, 110, 114, 128, 130, 135, 136, 138, 152, 154, 165, 170, 174, 182, 184, 186, 189, 190, 195, 222, 230, 231, 232, 238, 246, 248, 250, 255, 258, 266, 273, 282, 285, 286, 290, 296, 297

Offset

1,2

Comments

This sequence is actually the sequence of 4-multiplicatively perfect numbers all of whose elements (>1) have prime signature {7}, {1,3} or {1,1,1}.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

1 together with numbers with 8 divisors. - Vladeta Jovovic, Nov 12 2005

Mathematica

Select[Range[300], Surd[Times@@Most[Divisors[#]], 3]==#&] (* Harvey P. Dale, Nov 16 2015 *)

Prog

(PARI) isok(n) = {prd = 1; fordiv(n, d, prd = prd*d); prd == n^4; } \\ Michel Marcus, Oct 04 2013

Crossrefs

Cf. A048945, A111399. Essentially the same as A030626.

Cf. A030626, A007956.

Sequence in context: A372299 A334974 A048945 * A030626 A302571 A335054

Adjacent sequences: A111395 A111396 A111397 * A111399 A111400 A111401

Keyword

nonn

Author

Ant King, Nov 11 2005

Extensions

More terms from Michel Marcus, Oct 04 2013

Status

approved