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 A033307 Decimal expansion of Champernowne constant (or Mahler's number), formed by concatenating the positive integers. 148
 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 0, 1, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8, 1, 9, 2, 0, 2, 1, 2, 2, 2, 3, 2, 4, 2, 5, 2, 6, 2, 7, 2, 8, 2, 9, 3, 0, 3, 1, 3, 2, 3, 3, 3, 4, 3, 5, 3, 6, 3, 7, 3, 8, 3, 9, 4, 0, 4, 1, 4, 2, 4, 3, 4, 4, 4, 5, 4, 6, 4, 7, 4, 8, 4, 9, 5, 0, 5, 1, 5, 2, 5, 3, 5, 4, 5, 5, 5, 6, 5 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS This number is known to be normal in base 10. Named after David Gawen Champernowne (July 9, 1912 - August 19, 2000). - Robert G. Wilson v, Jun 29 2014 REFERENCES G. Harman, One hundred years of normal numbers, in M. A. Bennett et al., eds., Number Theory for the Millennium, II (Urbana, IL, 2000), 149-166, A K Peters, Natick, MA, 2002. C. A. Pickover, The Math Book, Sterling, NY, 2009; see p. 364. H. M. Stark, An Introduction to Number Theory. Markham, Chicago, 1970, p. 172. LINKS Harry J. Smith, Table of n, a(n) for n = 0..20000 D. H. Bailey and R. E. Crandall, Random Generators and Normal Numbers, Exper. Math. 11, 527-546, 2002. Maya Bar-Hillel and Willem A. Wagenaar, The perception of randomness, Advances in applied mathematics 12.4 (1991): 428-454. See page 428. Edward B. Burger, Diophantine Olympics and World Champions: Polynomials and Primes Down Under, Amer. Math. Monthly, 107 (Nov. 2000), 822-829. Chess Programming Wiki, David Champernowne (as of Dec. 2019). D. G. Champernowne, The Construction of Decimals Normal in the Scale of Ten, J. London Math. Soc., 8 (1933), 254-260. Arthur H. Copeland and Paul Erdős, Note on Normal Numbers, Bull. Amer. Math. Soc. 52, 857-860, 1946. Peyman Nasehpour, A Simple Criterion for Irrationality of Some Real Numbers, arXiv:1806.07560 [math.AC], 2018. Simon Plouffe, Champernowne constant, the natural integers concatenated Simon Plouffe, Champernowne constant, the natural integers concatenated Simon Plouffe, Generalized expansion of real constants Paul Pollack and Joseph Vandehey, Besicovitch, Bisection, and the normality of 0.(1)(4)(9)(16)(25)..., arXiv:1405.6266 [math.NT], 2014. Paul Pollack and Joseph Vandehey, Besicovitch, Bisection, and the Normality of 0.(1)(4)(9)(16)(25)..., The American Mathematical Monthly 122.8 (2015): 757-765. John K. Sikora, On the High Water Mark Convergents of Champernowne's Constant in Base Ten, arXiv:1210.1263 [math.NT], 2012. John K. Sikora, Analysis of the High Water Mark Convergents of Champernowne's Constant in Various Bases, arXiv:1408.0261 [math.NT], 2014. Eric Weisstein's World of Mathematics, Champernowne constant Wikipedia, Champernowne constant. Hector Zenil, N. Kiani and J. Tegner, Low Algorithmic Complexity Entropy-deceiving Graphs, arXiv preprint arXiv:1608.05972 [cs.IT], 2016. FORMULA Let "index" i = ceiling( W(log(10)/10^(1/9) (n - 1/9))/log(10) + 1/9 ) where W denotes the principal branch of the Lambert W function. Then a(n) = (10^((n + (10^i - 10)/9) mod i - i + 1) * ceiling((9n + 10^i - 1)/(9i) - 1)) mod 10. See also Mathematica code. - David W. Cantrell, Feb 18 2007 EXAMPLE 0.12345678910111213141516171819202122232425262728293031323334353637383940414243... MATHEMATICA Flatten[IntegerDigits/@Range[0, 57]] (* Or *) almostNatural[n_, b_] := Block[{m = 0, d = n, i = 1, l, p}, While[m <= d, l = m; m = (b - 1) i*b^(i - 1) + l; i++]; i--; p = Mod[d - l, i]; q = Floor[(d - l)/i] + b^(i - 1); If[p != 0, IntegerDigits[q, b][[p]], Mod[q - 1, b]]]; Array[ almostNatural[#, 10] &, 105] (* Robert G. Wilson v, Jul 23 2012 and modified Jul 04 2014 *) intermediate[n_] := Ceiling[FullSimplify[ProductLog[Log[10]/10^(1/9) (n - 1/9)] / Log[10] + 1/9]]; champerDigit[n_] := Mod[Floor[10^(Mod[n + (10^intermediate[n] - 10)/9, intermediate[n]] - intermediate[n] + 1) Ceiling[(9n + 10^intermediate[n] - 1)/(9intermediate[n]) - 1]], 10]; (* David W. Cantrell, Feb 18 2007 *) PROG (PARI) { default(realprecision, 20080); x=0; y=1; d=10.0; e=1.0; n=0; while (y!=x, y=x; n++; if (n==d, d=d*10); e=e*d; x=x+n/e; ); d=0; for (n=0, 20000, x=(x-d)*10; d=floor(x); write("b033307.txt", n, " ", d)); } \\ Harry J. Smith, Apr 20 2009 (Haskell) a033307 n = a033307_list !! n a033307_list = concatMap (map (read . return) . show) [1..] :: [Int] -- Reinhard Zumkeller, Aug 27 2013, Mar 28 2011 (Magma) &cat[Reverse(IntegerToSequence(n)):n in[1..50]]; // Jason Kimberley, Dec 07 2012 (Scala) val numerStr = (1 to 100).map(Integer.toString(_)).toList.reduce(_ + _) numerStr.split("").map(Integer.parseInt(_)).toList // Alonso del Arte, Nov 04 2019 (Python) from itertools import count def agen(): for k in count(1): yield from list(map(int, str(k))) a = agen() print([next(a) for i in range(104)]) # Michael S. Branicky, Sep 13 2021 CROSSREFS See A030167 for the continued fraction expansion of this number. A007376 is the same sequence but with a different interpretation. Cf. A007908, A000027, A001191 (concatenate squares). Tables in which the n-th row lists the base b digits of n: A030190 and A030302 (b = 2), A003137 and A054635 (b = 3), A030373 (b = 4), A031219 (b = 5), A030548 (b = 6), A030998 (b = 7), A031035 and A054634 (b = 8), A031076 (b = 9), A007376 and this sequence (b = 10). - Jason Kimberley, Dec 06 2012 Cf. A065648. Sequence in context: A169930 A048379 A333666 * A007376 A189823 A325479 Adjacent sequences: A033304 A033305 A033306 * A033308 A033309 A033310 KEYWORD nonn,base,cons,easy AUTHOR Eric W. Weisstein STATUS approved

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Last modified April 22 14:38 EDT 2024. Contains 371905 sequences. (Running on oeis4.)