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A210999 Composite numbers that are in the gap between an odd-indexed prime and an even-indexed prime. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 21 11:35 EST 2019. Contains 329370 sequences. (Running on oeis4.)