# [seqfan] Pi chunked to form a (self-describing) succession of odd and even terms

Eric Angelini Eric.Angelini at kntv.be
Tue Jun 22 19:38:38 CEST 2010

"a(0) = 3; for n>0, break up decimal expansion of Pi into chunks
that describe alternatively runs of odd and even parity terms":

P = 3,1,41,592,65,3,5,89,7,9,3,23,8462643,3,83,27,9,5028841,9,7,1,69,
3,9,9,3,7,5,105,8209,7,49,445,9,2307,81,64062862089,9,862803,4825,3,
421,1,7067,9,8,2,...

Example ('o' is for 'odd term' and 'E' for 'even term'):

P = 3,1,41,592,65,3,5,89,7,9,3,23,8462643,3,83,27,9,5028841,9,7,1,69,3,9,
o o  o  E   o o o  o o o o  o    o    o  o  o o    o    o o o  o o o
3     1                             41

9,3,7,5,105,8209,7,49,445,9,2307,81,64062862089,9,862803,4825,3,421,
o o o o  o    o  o  o  o  o   o   o       o     o    o     o  o  o

1,7067,9,8,2,...
o   o  o E E ...
592

... which is read: "In this seq there are 3 odd terms, followed by
1 even term, then 41 odd terms, then 592 even terms, etc.

This is not A136517:

http://www.research.att.com/~njas/sequences/A136517
"a(0) = 3; for n>0, break up decimal expansion of Pi into chunks
of increasing lengths; leading zeros are not printed."

Best,
É.
[if someone computes the next 592 (!) even terms, I'll be happy!)