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A197123 a(n) is the first n-digit substring to repeat in the decimal expansion of Pi. 2
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)
OFFSET

1,2

COMMENTS

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

LINKS

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.

EXAMPLE

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.

From Bobby Jacobs, Dec 24 2016: (Start)

1 appears at positions 1 and 3.

26 appears at positions 6 and 21.

592 appears at positions 4 and 61.

0582 appears at positions 50 and 132.

60943 appears at positions 397 and 551.

949129 appears at positions 496 and 1296.

8530614 appears at positions 4167 and 4601.

... (End)

CROSSREFS

Cf. A000796 (Pi), A159345 (the number of digits of Pi required to include the repeated string), A279860.

Sequence in context: A257518 A283343 A160059 * A203598 A262076 A057010

Adjacent sequences:  A197120 A197121 A197122 * A197124 A197125 A197126

KEYWORD

base,nonn

AUTHOR

Peter de Rivaz, Oct 10 2011

EXTENSIONS

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

STATUS

approved

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Last modified July 23 18:47 EDT 2017. Contains 289690 sequences.