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A181962
Numbers not expressed in form pi(n)+pi(sqrt(n)) with prime n.
1
3, 6, 12, 19, 35, 45, 68, 80, 108, 156, 173, 231, 276, 297, 344, 425, 504, 537, 628, 695, 726, 833, 909, 1024, 1188, 1278, 1321, 1409, 1452, 1553, 1908, 2008, 2174, 2224, 2524, 2583, 2766, 2953, 3082, 3281, 3477, 3554, 3911, 3989, 4134, 4210, 4674, 5154, 5323
OFFSET
1,1
COMMENTS
Or places of squares in A000430.
EXAMPLE
12 is in the sequence, since pi(23)+pi(sqrt(23))=9+2=11, while pi(29)+pi(sqrt(29))=10+3=13.
Also 12 is in the sequence since A000430(12)=25 is not prime.
MATHEMATICA
t = Table[PrimePi[n] + PrimePi[Sqrt[n]], {n, Prime[Range[10000]]}]; Complement[Range[t[[-1]]], t] (* T. D. Noe, Apr 09 2012 *)
CROSSREFS
Sequence in context: A125851 A351621 A209489 * A226220 A218076 A308722
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Apr 06 2012
STATUS
approved