A116012 - OEIS

%I #8 Jul 15 2021 06:35:10

%S 19,1873,147497,792736,4551733,4967176,7333813,8539521,8674128,

%T 12388853,12948373,18331664,24834369,36294936,50952310,116340016,

%U 170434387,196966352,222505713,236504256,286766145,390771936,426323088,532998481,778930925,805653001

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

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

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

%Y Cf. A116013, A116014, A116015.

%K nonn

%O 1,1

%A _Giovanni Resta_, Feb 13 2006

%E a(5)-a(26) from _Donovan Johnson_, Feb 17 2013