A101984 Numbers that occur exactly once in A101909 (= count of primes between 2n and 4n).

1, 3, 5, 8, 22, 36, 37, 46, 47, 48, 53, 63, 83, 98, 99, 101, 105, 108, 113, 114, 127, 135, 139, 148, 150, 155, 158, 171, 172, 173, 174, 175, 177, 178, 188, 205, 210, 218, 219, 220, 221, 226, 231, 240, 246, 254, 277, 282, 297, 298, 301, 303, 327, 333, 334, 339

Offset: 1

Author

Cino Hilliard, Jan 28 2005

Keywords

• easy
• nonn

Examples

			There are 5 primes between 16 and 32 and nowhere else between 2n and 4n.
		

Crossrefs

Cf. A101909, A101947, A101983, A101985.

Programs

PARI

bet2n4n(n)={ my(b=vecsort(vector(n,x, my(c=0); forprime(y=2*x+1,4*x-1, c++); c))); print1(1","); for(x=1,n-2, if(b[x+1]>b[x] && b[x+1]Don Reble. - M. F. Hasler, Sep 29 2019

Extensions

Better name from N. J. A. Sloane, Sep 29 2019

Corrected a(22) and a(45), following an observation by Don Reble. - M. F. Hasler, Sep 29 2019