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Search: id:A001999
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| A001999 |
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a(n+1) = a(n)(a(n)^2 - 3).
(Formerly M3055 N1239)
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+0
4
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| 3, 18, 5778, 192900153618, 7177905237579946589743592924684178, 369822356418414944143680173221426891716916679027557977938929258031490127514207143830378340325399155218
(list; graph; listen)
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OFFSET
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0,1
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REFERENCES
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E. B. Escott, Rapid method for extracting a square root, Amer. Math. Monthly, 44 (1937), 644-646.
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LINKS
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A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fib. Quart., 11 (1973), 429-437.
Index entries for sequences of form a(n+1)=a(n)^2 + ...
Eric Weisstein's World of Mathematics, Pierce Expansion
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FORMULA
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a(n) = 2*F(2*3^n+1)-F(2*3^n) = ceiling(tau^(2*3^n)) where F(k)=A000045(k) is the k-th Fibonacci number and tau is the golden ratio. - Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 29 2002
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PROGRAM
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(PARI) a(n)=2*fibonacci(2*3^n+1)-fibonacci(2*3^n)
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CROSSREFS
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Cf. A006276.
Sequence in context: A131489 A069854 A057133 this_sequence A101293 A078096 A139429
Adjacent sequences: A001996 A001997 A001998 this_sequence A002000 A002001 A002002
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KEYWORD
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nonn,easy,nice
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AUTHOR
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njas
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