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Numbers k such that the sum of the digits of pi(k)^prime(k) is divisible by k.
1

%I #7 Apr 10 2020 06:21:57

%S 1,10,35,63,106,153,602,1548,1710,4680,5274

%N Numbers k such that the sum of the digits of pi(k)^prime(k) is divisible by k.

%C Next term after 5274 is greater than 10000.

%C a(12) > 40000. - _Jinyuan Wang_, Apr 10 2020

%e The digits of pi(1548)^prime(1548) sum to 139320 and 139320 is divisible by 1548, so 1548 is in the sequence.

%t Do[k = PrimePi[n]^Prime[n]; s = Plus @@ IntegerDigits[k]; If[Mod[s, n] == 0, Print[n]], {n, 1, 10^4}]

%o (PARI) is(k) = sumdigits(primepi(k)^prime(k))%k == 0; \\ _Jinyuan Wang_, Apr 10 2020

%Y Cf. A007953.

%K nonn,base,hard,more

%O 1,2

%A _Ryan Propper_, Aug 08 2005