A193598 Even numbers k such that r(k) < r(k/2), where r(n) is the distance from n to the nearest prime.

2, 18, 30, 42, 52, 54, 66, 68, 70, 78, 90, 98, 100, 102, 110, 112, 114, 126, 128, 130, 138, 150, 152, 162, 172, 174, 182, 190, 198, 210, 222, 230, 232, 234, 236, 238, 240, 242, 244, 250, 258, 268, 270, 282, 284, 286, 290, 292, 294, 306, 308

Offset: 1

Author

Vladimir Shevelev, Jul 31 2011

Keywords

• nonn

Examples

			18 is in the sequence, since r(18) = 1 < 2 = r(9); 22 is not in the sequence, since r(22) = 1 >= 0 = r(11).
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

r(n) is A051699.

Programs

PARI

r(n)=min(nextprime(n)-n,n-precprime(n))
forstep(k=2,1e3,2,if(r(k)Charles R Greathouse IV, Jul 31 2011