A064777 Numbers k such that prime(k) - pi(k) is divisible by k.

1, 2, 3, 18, 42, 95, 524, 273585, 1735537, 4406057, 4406063, 4406188, 4406196, 4406341, 4406539, 4406541, 28703894, 73694240, 73694281, 73694287, 73694360, 73694363, 73694410, 3287860772, 3287860773, 3287860880, 3287860889, 3287860895, 3287860897

Offset: 1

Author

Labos Elemer and Robert G. Wilson v, Oct 18 2001

Keywords

• nonn

Examples

			k = 18 is a term: prime(18) = 61, pi(18) = 7, and (61-7)/18 = 54/18 = 3.
		

Crossrefs

Cf. A000040, A000720, A065139, A111181.

Programs

Mathematica

Do[ If[ IntegerQ[ (Prime[n] - PrimePi[n])/n ], Print[n]], {n, 1, 6*10^7} ]
Select[Range[5000000],Divisible[Prime[#]-PrimePi[#],#]&] (* Harvey P. Dale, Aug 12 2013 *)

PARI

isok(k) = ((prime(k) - primepi(k)) % k) == 0; \\ Michel Marcus, Jun 15 2021

Extensions

a(18)-a(23) from Donovan Johnson, Apr 23 2010

a(24)-a(29) from Donovan Johnson, Oct 17 2012