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 A008564 #23 Mar 23 2025 03:57:11
%S A008564 1,3,9,2,7,8,1,2,4,3,7,2,9,2,1,8,7,6,5,6,1,1,9,6,8,3,5,9,0,4,9,1,7,7,
%T A008564 1,4,7,5,3,1,4,4,1,1,5,9,4,3,2,3,4,7,8,2,9,6,9,1,4,3,4,8,9,0,7,4,3,0,
%U A008564 4,6,7,2,1,1,2,9,1,4,0,1,6,3,3,8,7,4,2,0,4,8,9,1,1,6,2,2,6,1,4,6,7,3
%N A008564 Digits of powers of 3.
%C A008564 Irregular table with row length sequence A034888. - _Jason Kimberley_, Nov 26 2012
%C A008564 The constant whose decimal expansion is this sequence is irrational (Mahler, 1981). - _Amiram Eldar_, Mar 23 2025
%H A008564 Muniru A Asiru, <a href="/A008564/b008564.txt">Table of n, a(n) for n = 0..5000</a>
%H A008564 Kurt Mahler, <a href="https://doi.org/10.1016/0022-314X(81)90010-X">On some irrational decimal fractions</a>, Journal of Number Theory, Vol. 13, No. 2 (1981), pp. 268-269.
%t A008564 Flatten[Table[IntegerDigits[3^n], {n, 0, 26}]] (* _Alonso del Arte_, Sep 29 2018 *)
%o A008564 (GAP) Flat(List([0..30],n->ListOfDigits(3^n))); # _Muniru A Asiru_, Sep 29 2018
%Y A008564 Cf. A000244, A034888.
%Y A008564 Cf. A000455, A008565, A008566, A008567, A008568, A008569, A008570, A008571, A008572, A008573, A010054.
%K A008564 nonn,base,easy,tabf
%O A008564 0,2
%A A008564 _N. J. A. Sloane_