A071394 Numbers n divisible by pi(n) [A057809] with prime pi(n); i.e., largest prime factor of n equals pi(n).

4, 6, 33, 335, 355, 3073, 8408, 64690, 481044, 1304693, 1304719, 3524318, 3524654, 9559785, 9559905, 70115803, 189963234, 189963918, 514278263, 1394194660, 3779856591, 10246935974, 75370122456, 204475052725, 204475053325, 1505578023783, 1505578024917

Offset: 1

Author

Jason Earls, Jun 12 2002

Keywords

• nonn

Examples

			pi(8408) = 1051 and 8408 = 2*2*2*1051.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..49

Crossrefs

Cf. A000720, A006530, A256394.

Programs

Mathematica

c = 0; lpf[n_] := If[ PrimeQ[n], c++; n, Transpose[ FactorInteger[n]][[1, -1]]]; Do[ If[ lpf[n] == c, Print[n]], {n, 2, 10^7}]
Select[Select[Range[2,10^6],IntegerQ[#/PrimePi[#]]&],PrimeQ[PrimePi[#]]&] (* Ivan N. Ianakiev, Apr 15 2015 *)
Select[Range[10^6], FactorInteger[#][[-1, 1]] == PrimePi@ # &] (* Michael De Vlieger, Jul 30 2017 *)

PARI

isok(n) = isprime(p=primepi(n)) && !(n % p); \\ Michel Marcus, Jul 31 2017

Formula

A000720(a(n)) = A006530(a(n)) = A256394(n). - Jonathan Sondow, Apr 15 2015

Extensions

Edited and extended by Robert G. Wilson v, Jun 13 2002

More terms from Hans Havermann, Jul 02 2002

a(26)-a(27) from Giovanni Resta, Mar 28 2017