A116012 Numbers k such that k + sigma(k) + sigma(sigma(k)) is a fourth power.

19, 1873, 147497, 792736, 4551733, 4967176, 7333813, 8539521, 8674128, 12388853, 12948373, 18331664, 24834369, 36294936, 50952310, 116340016, 170434387, 196966352, 222505713, 236504256, 286766145, 390771936, 426323088, 532998481, 778930925, 805653001

Offset

1,1

Links

Table of n, a(n) for n=1..26.

Example

792736 + sigma(792736) + sigma(sigma(792736)) = 56^4.

Prog

(PARI) for(n=1, 10^9, s=sigma(n); if(ispower(n+s+sigma(s), 4), print(n))) /* Donovan Johnson, Feb 17 2013 */

Crossrefs

Cf. A116013, A116014, A116015.

Sequence in context: A180394 A220990 A098846 * A203704 A087353 A355982

Adjacent sequences: A116009 A116010 A116011 * A116013 A116014 A116015

Keyword

nonn

Author

Giovanni Resta, Feb 13 2006

Extensions

a(5)-a(26) from Donovan Johnson, Feb 17 2013

Status

approved