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A083216
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Fibonacci-like sequence of composite numbers with a(0) = 20615674205555510, a(1) = 3794765361567513.
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8
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20615674205555510, 3794765361567513, 24410439567123023, 28205204928690536, 52615644495813559, 80820849424504095, 133436493920317654, 214257343344821749, 347693837265139403, 561951180609961152, 909645017875100555, 1471596198485061707, 2381241216360162262
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OFFSET
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0,1
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COMMENTS
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a(0) = 20615674205555510, a(1) = 3794765361567513. This is a second-order linear recurrence sequence with a(0) and a(1) coprime that does not contain any primes. It was found by Herbert Wilf in 1990.
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REFERENCES
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H. S. Wilf, Letters to the Editor, Math. Mag. 63, 1990.
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..1000
R. L. Graham, A Fibonacci-Like sequence of composite numbers, Math. Mag. 37 (1964) 322-324
Tanya Khovanova, Recursive Sequences
D. E. Knuth, A Fibonacci-Like sequence of composite numbers, Math. Mag. 63 (1) (1990) 21-25
J. W. Nicol, A Fibonacci-like sequence of composite numbers
Index to sequences with linear recurrences with constant coefficients, signature (1,1).
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FORMULA
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a(n) = a(n-1) + a(n-2) for n>1.
G.f.: (20615674205555510-16820908843987997*x)/(1-x-x^2).
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MAPLE
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a:= n-> (<<0|1>, <1|1>>^n. <<20615674205555510, 3794765361567513>>)[1, 1]:
seq(a(n), n=0..20); # Alois P. Heinz, Apr 04 2013
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PROG
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(PARI) Vec((20615674205555510-16820908843987997*x)/(1-x-x^2)+O(x^9)) \\ Charles R Greathouse IV, Sep 23 2012
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CROSSREFS
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Cf. A000032, A000045, A083103, A083104, A083105, A082411.
Sequence in context: A095432 A185434 A172655 * A180703 A145065 A080127
Adjacent sequences: A083213 A083214 A083215 * A083217 A083218 A083219
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KEYWORD
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nonn,easy
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AUTHOR
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Harry J. Smith, Apr 23 2003
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STATUS
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approved
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