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A042974
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n 1's followed by a 2.
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5
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1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1
(list; constant; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The number .121121112... is irrational - Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 05 2000
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REFERENCES
| C. V. Eynden, Problem 10439, Amer. Math. Monthly, 104 (1997), 873.
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LINKS
| Harry J. Smith, Table of n, a(n) for n = 1..20000
G. Xiao, Contfrac
Index entries for continued fractions for constants
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EXAMPLE
| 0.1211211121111211111211111121111111211111111211111111121111111111211111...
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PROG
| (PARI) a(n)=1+issquare(9+8*n) - Michael Somos, Jan 12 2000.
(PARI) { default(realprecision, 20080); x=0; for (n=1, 20000, x=10*x + 1 + issquare(9+8*n)); x/=10^19999; for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b042974.txt", n, " ", d)); } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), May 08 2009]
(Haskell)
a042974 n = a042974_list !! (n-1)
a042974_list = 1 : 2 :
concat (zipWith replicate (tail a042974_list) a042974_list)
-- Reinhard Zumkeller, Dec 08 2011
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CROSSREFS
| Cf. A042975, A056030 (continued fraction).
Sequence in context: A110955 A173264 A056731 * A020906 A191774 A097305
Adjacent sequences: A042971 A042972 A042973 * A042975 A042976 A042977
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KEYWORD
| nonn,easy,cons
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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