A259674 Numbers n such that the sum of the divisors of n equals the third power of the sum of the digits of n.

1, 714, 1065, 1173, 6486, 7755, 9951

Offset: 1

Author

Vincenzo Librandi, Aug 29 2015

Keywords

• nonn
• base
• less
• fini
• full

Examples

			714 is in the sequence because (1+2+3+6+7+14+17+21+34+42+ 51+102+119+238+357+714) = (7+1+4)^3 = 1728.
		

Crossrefs

Subsequence of A020477.

Cf. A000578, A055012, A260598.

Programs

Magma

[n: n in [1..10^7] | DivisorSigma(1,n) eq (&+Intseq(n)^3)];

Mathematica

n = 400000; list={}; x = 1; While[x<=n, If[DivisorSigma[1,x] == Total[IntegerDigits[x]]^3, AppendTo[list, x]]; x = x + 1]; list

PARI

isok(n) = sigma(n) == sumdigits(n)^3; \\ Michel Marcus, Sep 01 2015