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Search: id:A108156
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| A108156 |
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Numbers n such that a(n) is prime, where a(n) = a(n-1) + a(n-2), a(0) = 3794765361567513, a(1) = 20615674205555510. |
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1
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| 138, 163, 190, 523, 1855, 3228, 3579, 6468, 7170, 10230, 12783, 17259, 60139, 91315, 97923, 101823, 156075
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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In his biography of Paul Erdos, Hoffman cited Wilf's Fibonacci-like primefree sequence (A083216), but as Weisstein points out, Hoffman inadvertently switched the two initial terms, resulting in a sequence that appears primefree for the first 137 terms. Term 138 is 439351292910452432574786963588089477522344721, which is prime. The Mathematica program I'm including is from Weisstein's Mathematica notebook.
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REFERENCES
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P. Hoffman. The Man Who Loved Only Numbers: The Story of Paul Erdos and the Search for Mathematical Truth. New York: Hyperion, 1998.
H. S. Wilf. Letters to the Editor. Math. Mag. 63, 284, 1990.
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LINKS
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Eric Weisstein's World of Mathematics, Primefree Sequence.
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MATHEMATICA
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a[1] := 3794765361567513; a[2] := 20615674205555510; a[n_] := a[n] = a[n - 2] + a[n - 1]; Flatten[Position[Table[a[n], {n, 10^4}], _?PrimeQ]]
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CROSSREFS
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Cf. A083216.
Sequence in context: A107939 A008888 A045045 this_sequence A089518 A005447 A047652
Adjacent sequences: A108153 A108154 A108155 this_sequence A108157 A108158 A108159
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KEYWORD
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nonn
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AUTHOR
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Alonso Delarte (alonso.delarte(AT)gmail.com), Jun 06 2005
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EXTENSIONS
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a(10), a(11) and a(12) from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 07 2005
a(13) from Eric Weisstein (eric(AT)weisstein.com), Sep 23, 2005
a(14) from Eric Weisstein (eric(AT)weisstein.com), Oct 6, 2005)
a(15)-a(16) from Eric Weisstein (eric(AT)weisstein.com), Oct 10, 2005)
a(17) from Eric Weisstein (eric(AT)weisstein.com), Nov 9, 2005)
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