A210999 Composite numbers that are in the gap between an odd-indexed prime and an even-indexed prime.

6, 12, 18, 24, 25, 26, 27, 28, 32, 33, 34, 35, 36, 42, 48, 49, 50, 51, 52, 60, 68, 69, 70, 74, 75, 76, 77, 78, 84, 85, 86, 87, 88, 98, 99, 100, 104, 105, 106, 110, 111, 112, 128, 129, 130, 138, 150, 158, 159, 160, 161, 162, 168, 169, 170, 171, 172

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

Illustration of initial terms of three sequences:
A210998:       4,         8, 9, 10,             14, 15, 16
A000040: 2, 3,    5,    7,          11,     13,
A210999:             6,                 12,

Mathematica

Select[Range[4, 200], Not[PrimeQ[#]] && OddQ[PrimePi[#]] &] (* Alonso del Arte, Sep 26 2012 *)
Flatten[Range[First[#]+1, Last[#]-1]&/@Partition[Prime[Range[3, 50]], 2]] (* Harvey P. Dale, Oct 08 2012 *)

Crossrefs

Cf. A002808, A014689, A031215, A031368, A073170, A210998.

Sequence in context: A299909 A315752 A315753 * A037981 A044846 A037917

Adjacent sequences: A210996 A210997 A210998 * A211000 A211001 A211002

Keyword

nonn,easy

Author

Omar E. Pol, Sep 26 2012

Status

approved