A247345 a(1) = 16. For n > 1, a(n) is the position of the first occurrence of a(n-1) after the decimal point in the decimal expansion of Pi.

16, 40, 70, 96, 180, 3664, 24717, 15492, 84198, 65489, 3725, 16974, 41702, 3788, 5757, 1958, 14609, 62892, 44745, 9385, 169, 40, 70, 96, 180, 3664, 24717, 15492, 84198, 65489, 3725, 16974, 41702, 3788, 5757, 1958, 14609, 62892, 44745, 9385, 169, 40, 70, 96

Offset

1,1

Comments

After the first term, the sequence enters a repeating cycle of length 20.

According to the information on the website of Anderson, this sequence was discovered earlier by Dan Sikorsky.

First element a(1) = 61 leads after seven steps 61, 219, 716, 39, 43, 23, 16, ... into the same repeating cycle, same with a(1) = 71 after five steps 71, 39, 43, 23, 16, ... - Martin Renner, Feb 22 2020

Links

Table of n, a(n) for n=1..44.

D. Andersen, Loop Sequences within Pi, The Pi-Search Page.

Mathematica

L={16}; pi=ToString[ FromDigits@ RealDigits[Pi-3, 10, 10^5 ][[1]]]; Do[
AppendTo[L, StringPosition[ pi, ToString@ Last@ L, 1][[1, 1]]], {23}]; L (* Giovanni Resta, Jul 26 2015 *)

Crossrefs

Cf. A000796, A097614.

Sequence in context: A132161 A316562 A221684 * A332519 A177723 A174321

Adjacent sequences: A247342 A247343 A247344 * A247346 A247347 A247348

Keyword

nonn,base

Author

Felix Fröhlich, Jul 26 2015

Status

approved