A210998 Composite numbers that are in the gap between an even-indexed prime and an odd-indexed prime.

4, 8, 9, 10, 14, 15, 16, 20, 21, 22, 30, 38, 39, 40, 44, 45, 46, 54, 55, 56, 57, 58, 62, 63, 64, 65, 66, 72, 80, 81, 82, 90, 91, 92, 93, 94, 95, 96, 102, 108, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 132, 133, 134, 135, 136

Offset

1,1

Links

Table of n, a(n) for n=1..58.

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[#]] && EvenQ[PrimePi[#]] &] (* Alonso del Arte, Sep 26 2012 *)

Crossrefs

Cf. A002808, A014689, A031215, A031368, A073170, A210999.

Sequence in context: A080970 A288862 A274584 * A205524 A125493 A341615

Adjacent sequences: A210995 A210996 A210997 * A210999 A211000 A211001

Keyword

nonn,easy

Author

Omar E. Pol, Sep 26 2012

Status

approved