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A232014 Number of iterations of A032445 ("position of n in Pi") until a value is reached for the second time, when starting with n, or -1 if no value is repeated. 3
16, 4, 3, 5, 6, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

See A232013 for a variant based on A176341 instead of A032445.

Some loops: (5), (271070), (9292071), (40, 71), (2, 7, 14), (296, 1060, 13737, 133453, 646539, 294342, 141273). - Hans Havermann, Jul 26 2014

See Hans Havermann table (in links) for primary unknown-length evolutions. - Hans Havermann, Aug 06 2014

LINKS

Table of n, a(n) for n=0..5.

David G. Andersen, Loop Sequences within Pi, on The Pi-Search Page (Search 2*10^8 decimal digits of Pi).

Hans Havermann, Information table of n, a(n) for n=0..100.

Joaquin Navarro, Les secrets du nombre Pi (Book review, in French).

James Taylor, Irrational Numbers Search Engine (Search 2*10^9 decimal digits of Pi).

Ady Tzidon, Loops in Pi.

EXAMPLE

a(1)=4 since A032445(1)=2 (the first "1" occurs after the initial "3" as second digit in Pi), A032445(2)=7 (the first "2" occurs as 7th digit of Pi's decimal expansion), A032445(7)=14, A032445(14)=2, which "closes the loop" after 4 iterations. (The initial value does not need to be part of the loop.)

PROG

(PARI) A232014(n)={my(u=0); for(i=1, 9e9, u+=1<<n; bittest(u, n=A032445(n))&&return(i))}

CROSSREFS

Sequence in context: A040246 A075462 A082959 * A018814 A234288 A177499

Adjacent sequences:  A232011 A232012 A232013 * A232015 A232016 A232017

KEYWORD

nonn,base,more

AUTHOR

M. F. Hasler, Nov 16 2013

EXTENSIONS

Definition modified by N. J. A. Sloane, Jul 29 2014

STATUS

approved

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Last modified April 29 04:31 EDT 2017. Contains 285604 sequences.