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A075065
a(1) = 1 and then alternately even and odd composite numbers matching the parity of the index.
1
1, 4, 9, 6, 15, 8, 21, 10, 25, 12, 27, 14, 33, 16, 35, 18, 39, 20, 45, 22, 49, 24, 51, 26, 55, 28, 57, 30, 63, 32, 65, 34, 69, 36, 75, 38, 77, 40, 81, 42, 85, 44, 87, 46, 91, 48, 93, 50, 95, 52, 99, 54, 105, 56, 111, 58, 115, 60, 117, 62, 119, 64, 121, 66
OFFSET
1,2
MATHEMATICA
Module[{nn=150, comps, odds, evens, len}, comps=Complement[Range[nn], Prime[Range[ PrimePi[nn]]]]; odds=Select[ comps, OddQ]; evens=Select[comps, EvenQ]; len=Min[ Length[odds], Length[evens]]; Riffle[Take[odds, len], Take[evens, len]]] (* Harvey P. Dale, Feb 19 2013 *)
CROSSREFS
Cf. A075066.
Sequence in context: A335306 A261023 A171095 * A141553 A095065 A061207
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Sep 08 2002
EXTENSIONS
More terms from Harvey P. Dale, Feb 19 2013
STATUS
approved