A367035 Numbers k such that the greatest prime less than 2*k is less than twice the greatest prime less than k.

8, 14, 18, 20, 32, 33, 38, 39, 44, 48, 60, 61, 62, 63, 68, 72, 73, 74, 80, 81, 98, 102, 103, 104, 105, 108, 109, 110, 111, 128, 138, 140, 150, 151, 152, 153, 158, 164, 165, 168, 182, 183, 194, 198, 200, 212, 213, 214, 215, 224, 228, 230, 242, 243, 258, 259, 260, 264, 265, 266, 267, 268, 269, 270

Offset: 1

Author

Robert Israel, Dec 15 2023

Keywords

• nonn

Comments

Numbers k such that A049711(2 * k) > 2 * A049711(k).

Examples

			a(3) = 18 is a term because the greatest prime < 18 is 17, the greatest prime < 2*18 = 36 is 31, and 31 < 2 * 17.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Includes k+1 for k in A053176. Disjoint from A006254.

Cf. A049711, A151799.

Programs

Maple

select(k -> prevprime(2*k) < 2*prevprime(k), [$3..300]);

PARI

isok(k) = precprime(2*k-1) < 2*precprime(k-1); \\ Michel Marcus, Dec 16 2023