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Search: id:A155949
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| A155949 |
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Numbers p with property that p and 5 iterations of f(p) all are primes, where f(p)=p^2+p+41. |
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| 16355881, 109909799, 156177433, 167667607, 169177649, 196805633, 320142863, 428366489, 610038257, 644062919, 1103804483, 1164167891, 1184418737, 1493813903, 1541169463, 1882406467, 1956211891, 2018075911, 2248153673
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Next term a(20)=2493493447.
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EXAMPLE
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f(n)=n^2+n+41
n=1, p=16355881:
f(p)=267514859642083 prime,
f(f(p))=71564200129323635349724221013, prime
f(f(f(p))) =5121434740149885026514070854977073540325438908499394967223, prime
f(f(f(f(p)))) prime, f(f(f(f(f(p))))) prime, f(f(f(f(f(f(p)))))) not-prime.
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CROSSREFS
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Sequence in context: A004673 A058909 A105650 this_sequence A034598 A011574 A022540
Adjacent sequences: A155946 A155947 A155948 this_sequence A155950 A155951 A155952
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Jan 31 2009
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