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Search: id:A163848
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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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+0
2
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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; listen)
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OFFSET
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1,1
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EXAMPLE
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7-4=3, 9-7=2; 11-9=2, 16-11=5; 23-16=7, 25-23=2; ..
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MATHEMATICA
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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
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PROGRAM
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(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
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Sequence in context: A082496 A107133 A079138 this_sequence A111671 A140111 A118072
Adjacent sequences: A163845 A163846 A163847 this_sequence A163849 A163850 A163851
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KEYWORD
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nonn,new
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 05 2009
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EXTENSIONS
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Program and editing by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Nov 02 2009
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