This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A021247 #23 Jul 13 2025 16:27:33
%S A021247 0,0,4,1,1,5,2,2,6,3,3,7,4,4,8,5,5,9,6,7,0,7,8,1,8,9,3,0,0,4,1,1,5,2,
%T A021247 2,6,3,3,7,4,4,8,5,5,9,6,7,0,7,8,1,8,9,3,0,0,4,1,1,5,2,2,6,3,3,7,4,4,
%U A021247 8,5,5,9,6,7,0,7,8,1,8,9,3,0,0,4,1,1,5,2,2,6,3,3,7,4,4,8,5,5,9
%N A021247 Decimal expansion of 1/243.
%C A021247 Period 27 Repeat: [0, 0, 4, 1, 1, 5, 2, 2, 6, 3, 3, 7, 4, 4, 8, 5, 5, 9, 6, 7, 0, 7, 8, 1, 8, 9, 3]. - _Wesley Ivan Hurt_, May 25 2014
%H A021247 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/243.html">243</a>.
%H A021247 <a href="/index/Rec#order_27">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).
%F A021247 1/243 = 1/3^5. - _M. F. Hasler_, Apr 23 2021
%e A021247 0.00411522633744855967078189300411522633744855967078189300411522633744855967078...
%p A021247 Digits:=100; evalf(1/243); # _Wesley Ivan Hurt_, May 25 2014
%t A021247 RealDigits[1/243, 10, 100, -1][[1]] (* _Wesley Ivan Hurt_, May 25 2014; corrected by _Harvey P. Dale_, Jan 23 2019 *)
%t A021247 PadRight[{},120,{0,0,4,1,1,5,2,2,6,3,3,7,4,4,8,5,5,9,6,7,0,7,8,1,8,9,3}] (* _Harvey P. Dale_, Jan 23 2019 *)
%o A021247 (PARI) A021247_upto(N=100)={localprec(N+3);digits((1/3^5+1)\.1^N)[^1]} \\ _M. F. Hasler_, Apr 23 2021
%Y A021247 Cf. A010701 (1/3), A000012 (1/3^2), A021085 (1/3^4), A021733 (1/3^6).
%Y A021247 Cf. A068542 (period of the fraction 1/3^n).
%K A021247 nonn,cons
%O A021247 0,3
%A A021247 _N. J. A. Sloane_, Dec 11 1996