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A226567
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Numbers n such that 2n+1 is neither a square nor a prime.
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1
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7, 10, 13, 16, 17, 19, 22, 25, 27, 28, 31, 32, 34, 37, 38, 42, 43, 45, 46, 47, 49, 52, 55, 57, 58, 59, 61, 62, 64, 66, 67, 70, 71, 72, 73, 76, 77, 79, 80, 82, 85, 87, 88, 91, 92, 93, 94, 97, 100, 101, 102, 103, 104, 106, 107, 108, 109, 110, 115, 117, 118, 121
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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n=10; n+1=11; 121-100=21; 21 is not a square nor a prime.
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MAPLE
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remove(n -> issqr(2*n+1) or isprime(2*n+1), [$1..1000]); # Robert Israel, Jun 16 2017
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MATHEMATICA
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Select[Range[200], ! PrimeQ[2 # + 1] && ! IntegerQ[Sqrt[2 # + 1]] &] (* T. D. Noe, Jun 13 2013 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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