cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A297927 Decimal expansion of ratio of number of 1's to number of 2's in A293630.

Original entry on oeis.org

2, 6, 3, 2, 9, 0, 4, 5, 5, 5, 1, 7, 9, 0, 6, 5, 9, 4, 5, 7, 9, 8, 7, 2, 8, 5, 5, 6, 7, 5, 3, 5, 9, 7, 4, 5, 7, 1, 1, 5, 5, 7, 0, 6, 2, 9, 0, 9, 8, 6, 4, 2, 3, 8, 0, 2, 3, 2, 2, 2, 0, 3, 4, 7, 4, 9, 3, 2, 5, 9, 4, 7, 2, 2, 1, 3, 0, 6, 9, 1, 2, 1, 3, 5, 6, 1, 9
Offset: 1

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Author

Iain Fox, Jan 08 2018

Keywords

Comments

Equals (2 - d)/(d - 1), where d = lim_{k->infinity} (1/k)*Sum_{i=1..k} A293630(i) = 1.275261... (see A296564).
See comments from Jon E. Schoenfield on A296564 for explanation of PARI program.
Is this number transcendental?

Examples

			Equals 2.6329045551790659457987285567535974571155706290...
After generating k steps of A293630:
  k = 0:        [1, 2];                  1
  k = 1:        [1, 2, 1, 1];            3
  k = 2:        [1, 2, 1, 1, 1, 2, 1];   2.5
  k = 3:        [1, 2, 1, 1, 1, 2, ...]; 2.25
  k = 4:        [1, 2, 1, 1, 1, 2, ...]; 2.7
  k = 5:        [1, 2, 1, 1, 1, 2, ...]; 2.65
  k = 6:        [1, 2, 1, 1, 1, 2, ...]; 2.625
  ...
  k = infinity: [1, 2, 1, 1, 1, 2, ...]; 2.632904555179...
		

Crossrefs

Programs

  • PARI
    gen(build) = {
    my(S = [1, 2], n = 2, t = 3, L, nPrev, E);
    for(j = 1, build, L = S[#S]; n = n*(1+L)-L; t = t*(1+L)-L^2; nPrev = #S; for(r = 1, L, for(i = 1, nPrev-1, S = concat(S, S[i]))));
    E = S;
    for(j = build + 1, build + #E, L = E[#E+1-(j-build)]; n = n*(1+L)-L; t = t*(1+L)-L^2);
    return(1.0*(2 - t/n)/(t/n - 1))
    } \\ (gradually increase build to get more precise answers)

Extensions

Terms after a(3) corrected by Iain Fox, Jan 16 2018