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A163848
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Primes p such that the differences between p and the closest squares surrounding p are primes.
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1
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7, 11, 23, 47, 83, 167, 227, 443, 1223, 1367, 1847, 2027, 3023, 3251, 5039, 5927, 9803, 11447, 13691, 14639, 16127, 21611, 24023, 36479, 44519, 47087, 49727, 50627, 54287, 61007, 64007, 65027, 88211, 90599, 95483, 103043, 104327, 123203, 137639
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 7-4=3, 9-7=2; 11-9=2, 16-11=5; 23-16=7, 25-23=2; ..
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MATHEMATICA
| Clear[f, lst, p, n]; f[n_]:=IntegerPart[Sqrt[n]]; lst={}; Do[p=Prime[n]; If[PrimeQ[p-f[p]^2]&&PrimeQ[(f[p]+1)^2-p], AppendTo[lst, p]], {n, 8!}]; lst
spQ[n_]:=Module[{lsq=Floor[Sqrt[n]]}, And@@PrimeQ[{n-lsq^2, (lsq+1)^2-n}]]; Select[Prime[Range[140000]], spQ] (* From Harvey P. Dale, May 08 2011 *)
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PROG
| (PARI) forstep(n=3, 1e6, 2, if(isprime(2*n-3)&&isprime(k=n^2-2), print1(k", ")); if(isprime(2*n-1)&&isprime(k=n^2+2), print1(k", ")))
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CROSSREFS
| Sequence in context: A082496 A107133 A079138 * A111671 A140111 A118072
Adjacent sequences: A163845 A163846 A163847 * A163849 A163850 A163851
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KEYWORD
| nonn
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AUTHOR
| Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 05 2009
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EXTENSIONS
| Program and editing by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Nov 02 2009
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