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A128938
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Numbers n such that n(n+1) plus the n-th prime is a prime.
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1
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3, 5, 7, 9, 10, 11, 12, 13, 20, 27, 28, 32, 33, 35, 36, 41, 42, 43, 45, 47, 49, 54, 63, 65, 74, 75, 84, 91, 94, 95, 98, 104, 105, 107, 109, 113, 114, 117, 122, 124, 126, 128, 129, 135, 140, 149, 152, 155, 160, 164, 168, 171, 189, 190, 192, 199, 203, 209, 212, 214, 216
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OFFSET
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1,1
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LINKS
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EXAMPLE
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Given that 23 is the 9th prime, take 9*10 + 23 = 113, a prime.
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MAPLE
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a:=proc(n) if isprime(n*(n+1)+ithprime(n))=true then n else fi end: seq(a(n), n=1..270); # Emeric Deutsch, May 05 2007
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MATHEMATICA
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Select[Range[300], PrimeQ[#(#+1)+Prime[#]]&] (* Harvey P. Dale, Mar 18 2018 *)
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PROG
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(PARI) isok(n) = isprime(prime(n)+n+n^2); \\ Michel Marcus, Mar 13 2016
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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