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

1,2

Links

Table of n, a(n) for n=1..7.

Example

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.

Mathematica

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

Prog

(Magma) [n: n in [1..10^7] | DivisorSigma(1, n) eq (&+Intseq(n)^3)];
(PARI) isok(n) = sigma(n) == sumdigits(n)^3; \\ Michel Marcus, Sep 01 2015

Crossrefs

Subsequence of A020477.

Cf. A000578, A055012, A260598.

Sequence in context: A265142 A251031 A256509 * A321493 A260282 A360358

Adjacent sequences: A259671 A259672 A259673 * A259675 A259676 A259677

Keyword

nonn,base,less,fini,full

Author

Vincenzo Librandi, Aug 29 2015

Status

approved