This site is supported by donations to The OEIS Foundation.



Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 4500 articles have referenced us, often saying "we would not have discovered this result without the OEIS".

(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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: A058461 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



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified December 1 20:33 EST 2015. Contains 264709 sequences.