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A116888
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Primes p that remain prime through 4 iterations of function f(p)=p^2+4.
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3
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306167, 48639197, 64695713, 68252687, 87788237, 87813293, 160486967, 255974437, 283032247, 324609913, 361705873, 417684523, 449364197, 451995587, 454052213, 466037563, 536504713, 574746467, 596095613
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| p=306167, f(p)= 93738231893, f(f(p))= 8786856118425842363453, f(f(f(p)))= 77208840445917661077402487029419236950083213 and the 88-digits f(f(f(f(p)))) are all prime numbers.
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MATHEMATICA
| Select[Prime[Range[9! ]], PrimeQ[ #^2+4]&&PrimeQ[(#^2+4)^2+4]&&PrimeQ[((#^2+4)^2+4)^2+4]&&PrimeQ[(((#^2+4)^2+4)^2+4)^2+4]&] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Feb 26 2010]
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CROSSREFS
| Cf. A062324, A116886, A116887, A116889.
Sequence in context: A183641 A185852 A053849 * A206276 A127491 A205204
Adjacent sequences: A116885 A116886 A116887 * A116889 A116890 A116891
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KEYWORD
| nonn
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AUTHOR
| Giovanni Resta (g.resta(AT)iit.cnr.it), Feb 27 2006
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