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A197123 a(n) is the first n-digit substring to repeat in the decimal expansion of Pi. 1
1, 26, 592, 582, 60943, 949129, 8530614, 52637962, 201890888, 4392366484, 89879780761, 756130190263, 3186120489507, 18220874234996, 276854551127715, 8230687217052243, 93415455347042966, 13724950651727463 (list; graph; refs; listen; history; text; internal format)



a(4) is written in the sequence as a 3-digit number 582 because the repeating substring is the 4-digit number 0582.

a(18) should also have a leading zero: 013724950651727463. This value starts at digit 378,355,223 and at digit 1,982,424,643. This computation was performed by Richard Tobin. - Clive Tooth, Mar 06 2012


Table of n, a(n) for n=1..18.

Dave Andersen, The Pi-Search Page.

David H. Bailey, The computation of pi to 29,360,000 decimal digits using Borweins' quartically convergent algorithm, Mathematics of Computation 50 (1988), pp. 283-296.


For n=2 the a(2)=26 solution is because if we look at all the 2-digit substrings 14,41,15,59,92,26,... of the decimal expansion of Pi=3.1415926535897932384626 we find that the first 2-digit substring to appear twice is 26.


Cf. A000796 (Pi), A159345 (the number of digits of Pi required to include the repeated string).

Sequence in context: A265461 A257518 A160059 * A203598 A262076 A057010

Adjacent sequences:  A197120 A197121 A197122 * A197124 A197125 A197126




Peter de Rivaz, Oct 10 2011


a(16)-a(18) from Clive Tooth, Mar 06 2012



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Last modified February 6 03:45 EST 2016. Contains 268029 sequences.