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A244570
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Smallest prime p >= prime(n) such that p*prime(n)+2 is prime.
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6
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3, 7, 11, 19, 17, 37, 23, 37, 43, 47, 47, 61, 53, 73, 109, 79, 89, 71, 109, 227, 113, 97, 139, 137, 127, 149, 127, 131, 283, 137, 139, 181, 173, 151, 167, 191, 173, 193, 193, 181, 239, 199, 233, 223, 239, 251, 239, 241, 233, 313, 241, 251, 271, 277, 373, 271
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OFFSET
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2,1
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COMMENTS
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LINKS
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MATHEMATICA
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a[n_] := For[p = Prime[n], True, p = NextPrime[p], If[PrimeQ[p Prime[n] + 2], Return[p]]];
sp[n_]:=Module[{p=n}, While[CompositeQ[p*n+2], p=NextPrime[p]]; p]; Table[ sp[k], {k, Prime[Range[2, 60]]}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 19 2020 *)
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PROG
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(PARI) s=[]; for(n=2, 100, p=q=prime(n); while(!isprime(p*q+2), p=nextprime(p+1)); s=concat(s, p)); s \\ Colin Barker, Jun 30 2014
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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