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Search: id:A058181
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| A058181 |
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Quadratic recurrence a(n)=a(n-1)^2-a(n-2), a(0)=1,a(1)=0. |
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+0
2
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| 1, 0, -1, 1, 2, 3, 7, 46, 2109, 4447835, 19783236185116, 391376433956083065015485621, 153175513056180249189030531428945090978436751221570525
(list; graph; listen)
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OFFSET
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0,5
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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 + ...
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FORMULA
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a(n)^2=a(n+1)+a(n-1), a(-1-n)=a(n).
For n>=4, a(n)=ceil(c^(2^n)) with c=1.0303497388742578142745024606710866\
16436302563960998408889321488508667424048981473368773165340730475719244472111...
and c^(1/4)=1.0075025785879710605024343257517358... - Benoit Cloitre, Apr 16 2007
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EXAMPLE
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a(8)=a(7)^2-a(6)=3^2-2=7
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PROGRAM
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(PARI) a(n)=if(n<0, a(-1-n), if(n<2, 1-n, a(n-1)^2-a(n-2))) /* Michael Somos May 05 2005 */
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CROSSREFS
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Cf. A058182.
Sequence in context: A068393 A032053 A086542 this_sequence A090593 A030090 A075461
Adjacent sequences: A058178 A058179 A058180 this_sequence A058182 A058183 A058184
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KEYWORD
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sign
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), Nov 15 2000
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