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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
OFFSET
1,1
LINKS
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
KEYWORD
nonn,easy
AUTHOR
Omar E. Pol, Sep 26 2012
STATUS
approved