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

1,1

Links

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

Formula

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

Example

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

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 *)

Prog

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

Crossrefs

Cf. A000720, A006530, A256394.

Sequence in context: A164127 A180139 A222490 * A137021 A176002 A175061

Adjacent sequences: A071391 A071392 A071393 * A071395 A071396 A071397

Keyword

nonn

Author

Jason Earls, Jun 12 2002

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

Status

approved