A194351 Starting position of the first occurrence of a string of 2^n in the decimal expansion of Pi.
1, 6, 2, 11, 40, 15, 22, 148, 1750, 1842, 12735, 26862, 27372, 2943, 37619, 39587, 106920, 820238, 76875, 47887, 6150809, 3660438, 17376657, 15416321, 162454456, 132295965, 265234498, 33844308, 4847933000, 671531549, 1122335995, 2894348872, 763748417
Offset: 0
Examples
Pi = 3.141592653589793238462643383279502884197169399375105.. The '1' (2^0) after the decimal point is at position 1. The '1' of the first occurrence of '16' (2^4) is at position 40.
Links
- Dmitry Petukhov, Table of n, a(n) for n = 0..45
- Timothy Mullican, 50 trillion digits of pi
- Peter Trüb, 22.4 trillion digits of pi
Programs
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Mathematica
d = ToString[N[Pi-3, 1000000]]; Table[pos = StringPosition[d, ToString[2^n], 1]; If[pos == {}, Print["not enough digits for ", 2^n]; pos = 0, pos = pos[[1, 1]] - 2], {n, 0, 19}] (* T. D. Noe, Sep 02 2011 *)
Formula
a(n) = A032445(2^n)-1. - R. J. Mathar, Sep 02 2011
Extensions
Terms corrected by D. S. McNeil, Sep 02 2011
a(29), a(32) from D. S. McNeil, Sep 03 2011
Edited by Hans Havermann, Jul 22 2014
a(28), a(30)-a(31) from Hans Havermann, Jul 22 2014
a(33)-a(43), a(45) from Dmitry Petukhov, Jan 27 2020
a(44) from Dmitry Petukhov, Oct 27 2021
Comments