A083607 Starting positions of strings of four 2's in the decimal expansion of Pi.

4902, 7964, 12486, 43405, 50271, 55736, 62920, 65260, 65261, 71778, 83521, 97191, 98423, 103025, 105290, 123462, 125053, 125172, 125656, 138493, 138655, 150949, 162191, 192255, 196397, 204561, 204850, 209562, 216368, 216660, 267139, 272809

Offset: 1

Author

Rick L. Shepherd, May 01 2003

Keywords

• base
• nonn

Links

• Dave Andersen, Pi-Search Page
• Eric Weisstein's World of Mathematics, Pi Digits.
• Index entries for sequences related to the number Pi

Crossrefs

Cf. A083606 (three 2's), A083608 (five 2's).

Programs

Mathematica

$MaxPrecision=10^8;a=RealDigits[Pi,10,9! ];lst={};Do[b=a[[1]][[n]];c=a[[1]][[n+1]];d=a[[1]][[n+2]];e=a[[1]][[n+3]];If[b==2&&c==2&&d==2&&e==2,AppendTo[lst,n-1]],{n,6*6!,9!-3}];lst (* Vladimir Joseph Stephan Orlovsky, Jun 07 2009 *)
With[{p=Partition[Rest[RealDigits[Pi,10,300000][[1]]],4,1]}, Flatten[ Position[ p,{2,2,2,2}]]] (* Harvey P. Dale, Oct 10 2011 *)
Module[{nn=300000,pid},pid=RealDigits[Pi,10,nn][[1]];SequencePosition[ pid,{2,2,2,2}]][[All,1]]-1 (* Harvey P. Dale, Jan 13 2023 *)