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A004603 Expansion of Pi in base 4.

%I A004603 #54 Aug 17 2022 16:21:00
%S A004603 3,0,2,1,0,0,3,3,3,1,2,2,2,2,0,2,0,2,0,1,1,2,2,0,3,0,0,2,0,3,1,0,3,0,
%T A004603 1,0,3,0,1,2,1,2,0,2,2,0,2,3,2,0,0,0,3,1,3,0,0,1,3,0,3,1,0,1,0,2,2,1,
%U A004603 0,0,0,2,1,0,3,2,0,0,2,0,2,0,2,2,1,2,1,3,3,0,3,0,1,3,1,0,0,0,0,2,0,0,2,3,2
%N A004603 Expansion of Pi in base 4.
%C A004603 Theoretically, this sequence could be used to encode a given number of digits of Pi as a DNA sequence, which could then be read back from one helix. The value read back from the other helix would of course depend on the assignment of G, A, C, T to the digits 0, 1, 2, 3. - _Alonso del Arte_, Nov 07 2011
%H A004603 G. C. Greubel, <a href="/A004603/b004603.txt">Table of n, a(n) for n = 1..10000</a>
%H A004603 Francisco Javier Aragón Artacho, <a href="http://gigapan.com/gigapans/106803">100 billion step walk on the digits of pi</a>
%H A004603 F. J. Aragon Artacho, D. H. Bailey, J. M. Borwein, P. B. Borwein, J. Fountain, and M. Skerritt <a href="https://walks.carma.newcastle.edu.au/">Walking on numbers: a multiple media mathematics project</a>, 2012.
%H A004603 Elias Bröms, <a href="http://www.befria.nu/elias/pi/lookpi.html">Pictures of Pi</a>
%F A004603 a(n) = 2*A004601(2n) + A004601(2n+1). - _Jason Kimberley_, Nov 08 2012
%e A004603 3.02100333122220202011220300203103010301...
%t A004603 RealDigits[Pi, 4, 100][[1]]
%t A004603 Table[ResourceFunction["NthDigit"][Pi, n, 4], {n, 1, 100}] (* _Joan Ludevid_, Jul 04 2022; easy to compute a(10000000)=2 with this function; requires Mathematica 12.0+ *)
%Y A004603 Pi in base b: A004601 (b=2), A004602 (b=3), this sequence (b=4), A004604 (b=5), A004605 (b=6), A004606 (b=7), A006941 (b=8), A004608 (b=9), A000796 (b=10), A068436 (b=11), A068437 (b=12), A068438 (b=13), A068439 (b=14), A068440 (b=15), A062964 (b=16), A060707 (b=60).
%Y A004603 Cf. A007514.
%Y A004603 Cf. A004595, A004541. - _Jason Kimberley_, Dec 01 2012
%K A004603 nonn,base,cons,easy
%O A004603 1,1
%A A004603 _N. J. A. Sloane_