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 A309474 #18 Aug 05 2019 15:30:48 %S A309474 1,2,1,2,2,1,2,0,1,1,1,0,2,1,2,0,1,2,0,1,0,0,1,2,0,2,1,1,1,2,2,2,1,0, %T A309474 1,2,1,2,1,1,2,1,2,0,0,1,2,1,1,1,0,1,0,1,2,1,2,1,2,2,0,2,1,0,1,2,1,0, %U A309474 2,1,2,1,0,2,1,2,2,0,2,1,1,2,0,2,0,2,0,2,2,0,2,2,0,0,0,1,2 %N A309474 Digits of one of the two 3-adic integers sqrt(-1/2). %H A309474 Robert Israel, <a href="/A309474/b309474.txt">Table of n, a(n) for n = 0..10000</a> %F A309474 p = ...122121, p^2 = ...111111. %F A309474 q = A271223 = ...200211, p * q = ...000001. %F A309474 a(n) = (b(n+1) - b(n))/3^n, with b(n) = A309476(n). %p A309474 T:= select(t -> padic:-ratvaluep(t,1)=1, [padic:-rootp(x^2+1/2,3,100)]): %p A309474 op([1,1,3],T); # _Robert Israel_, Aug 05 2019 %o A309474 (PARI) Vecrev(digits(truncate(sqrt(-1/2+O(3^100))), 3)) %Y A309474 Cf. A271223, A309475, A309476. %K A309474 nonn,base %O A309474 0,2 %A A309474 _Seiichi Manyama_, Aug 04 2019