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 A021030 Decimal expansion of 1/26. 1
 0, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8, 4, 6, 1, 5, 3, 8 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A tool code breakers sometimes use is the index of coincidence, I_c. According to Swenson (2008), "the theoretically perfect I_c is if all characters occur the exact same number of times so that none was more likely than any other to be repeated." For cyphertext encrypted from English text (using an alphabet of 26 letters) of infinite length, this means there exists the infinite limit (n - 1)/(26n - 1) which by L'Hopital's rule works out to 1/26. - Alonso del Arte, Sep 13 2011 Also continued fraction expansion of (sqrt(5317635) - 2067)/746.  - Bruno Berselli, Sep 13 2011 REFERENCES Christopher Swenson, Modern Cryptanalysis: Techniques for Advanced Code Breaking. Indianopolis, Indiana: Wiley Publishing Inc. (2008): 12 - 15 LINKS Index entries for linear recurrences with constant coefficients, signature (1,0,-1,1). FORMULA Contribution by Bruno Berselli, Sep 13 2011: (Start)   G.f.: x*(3+5*x-4*x^2+5*x^3)/((1-x)*(1+x)*(1-x+x^2)).   a(n) = a(n-1) - a(n-3) + a(n-4) for n > 4.   a(n) = (1/30)*(-11*(n mod 6)+34*((n+1) mod 6) - ((n+2) mod 6) + 29*((n+3) mod 6) - 16*((n+4) mod 6) + 19*((n+5) mod 6)) for n > 0. (End) EXAMPLE 0.03846153846153846153846153846... MATHEMATICA Join[{0}, RealDigits[1/26, 10, 120][[1]]] (* or *) PadRight[{0}, 120, {5, 3, 8, 4, 6, 1}] (* Harvey P. Dale, Dec 19 2012 *) CROSSREFS Sequence in context: A242030 A105722 A103559 * A276682 A303215 A240242 Adjacent sequences:  A021027 A021028 A021029 * A021031 A021032 A021033 KEYWORD nonn,cons,easy AUTHOR STATUS approved

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Last modified June 2 12:24 EDT 2020. Contains 334771 sequences. (Running on oeis4.)