A166028 - OEIS

A166028

a(n) is the starting position of the second occurrence of a string of the initial n decimal digits of e in the decimal expansion of e.

%I #3 Apr 01 2017 15:41:53

%S 4,62,918,5503,29169,252474,7910575,7910575

%N a(n) is the starting position of the second occurrence of a string of the initial n decimal digits of e in the decimal expansion of e.

%C The digits 2 7 1 8 2 ... are labeled 0, 1, 2, 3, 4, ...

%C The next term, a(9), is greater than 50 million. - _Harvey P. Dale_, Apr 01 2017

%e a(6) is the starting position of the second occurrence of the initial 6 decimals of e. the string '271828' occurs at position 252,474, thus a(6) = 252,474.

%t Module[{nn=300000,ed},ed=RealDigits[E,10,nn][[1]];Table[ SequencePosition[ ed, Take[ed,n],2][[2]],{n,6}][[All,1]]-1] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 01 2017 *)

%Y Cf. A001113, A081876

%K base,nonn

%O 1,1

%A Steven Lubars (lubars(AT)gmail.com), Oct 04 2009

%E Two more terms -- a(7) and a(8) -- from _Harvey P. Dale_, Apr 01 2017