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 A309475 #17 Aug 05 2019 15:30:38 %S A309475 2,0,1,0,0,1,0,2,1,1,1,2,0,1,0,2,1,0,2,1,2,2,1,0,2,0,1,1,1,0,0,0,1,2, %T A309475 1,0,1,0,1,1,0,1,0,2,2,1,0,1,1,1,2,1,2,1,0,1,0,1,0,0,2,0,1,2,1,0,1,2, %U A309475 0,1,0,1,2,0,1,0,0,2,0,1,1,0,2,0,2,0,2,0,0,2,0,0,2,2,2,1,0,2,2,2 %N A309475 Digits of one of the two 3-adic integers sqrt(-1/2). Here the sequence with first digit 2. %H A309475 Robert Israel, <a href="/A309475/b309475.txt">Table of n, a(n) for n = 0..10000</a> %F A309475 p = ...100102, p^2 = ...111111. %F A309475 q = A271224 = ...022012, p * q = ...000001. %F A309475 a(n) = (b(n+1) - b(n))/3^n, with b(n) = A309477(n). %p A309475 T:= select(t -> padic:-ratvaluep(t, 1)=2, [padic:-rootp(x^2+1/2, 3, 100)]): op([1, 1, 3], T); # _Robert Israel_, Aug 05 2019 %o A309475 (PARI) Vecrev(digits(truncate(-sqrt(-1/2+O(3^100))), 3)) %Y A309475 Cf. A271224, A309474, A309477. %K A309475 nonn,base %O A309475 0,1 %A A309475 _Seiichi Manyama_, Aug 04 2019