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

Author

Ant King, Nov 11 2005

Keywords

• nonn

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

Crossrefs

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

Cf. A030626, A007956.

Programs

Mathematica

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

PARI

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

Formula

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

Extensions

More terms from Michel Marcus, Oct 04 2013