A074810 Numbers k such that the number of primes between k and 2k (inclusive) = largest prime factor of k.

1, 2, 4, 8, 9, 28, 65, 114, 174, 186, 246, 623, 1784, 1832, 1912, 5121, 13810, 14090, 39413, 40403, 808822, 809858, 810026, 2201505, 2202735, 6047408, 6048656, 16463939, 16467271, 16472371, 121482371, 121495747, 330358060, 898100679

Offset: 1

Author

Jason Earls, Sep 08 2002

Keywords

• nonn

Examples

			28 is a term because there are 7 primes between n = 28 and 2n = 56: 29, 31, 37, 41, 43, 47, 53; and the largest prime dividing 28 is 7.
		

Crossrefs

Cf. A006530, A035250.

Programs

Maple

with(numtheory): a:=proc(n) if pi(2*n)-pi(n-1)=max(1, factorset(n)) then n fi end: seq(a(n), n=1..1000); # Emeric Deutsch, Feb 05 2006

Extensions

More terms from Emeric Deutsch, Feb 05 2006

a(24)-a(34) from Donovan Johnson, Apr 23 2010