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 A118829 #4 Mar 30 2012 18:36:57 %S A118829 1,-2,-1,2,1,0,1,-8,-7,6,-1,10,9,-8,1,-24,-23,22,-1,26,25,-24,1,-32, %T A118829 -31,30,-1,34,33,-32,1,-64,-63,62,-1,66,65,-64,1,-72,-71,70,-1,74,73, %U A118829 -72,1,-88,-87,86,-1,90,89,-88,1,-96,-95,94,-1,98,97,-96,1,-160,-159,158,-1,162,161,-160,1,-168,-167,166,-1,170,169 %N A118829 Denominators of the convergents of the 2-adic continued fraction of zero given by A118827. %F A118829 a(4*n) = -(-1)^n*2*A080277(n); a(4*n+1) = -(-1)^n*(2*A080277(n)-1); a(4*n+2) = (-1)^n*(2*A080277(n)-2); a(4*n-1) = (-1)^n. %e A118829 For n>=1, convergents A118828(k)/A118829(k) are: %e A118829 at k = 4*n: -1/(2*A080277(n)); %e A118829 at k = 4*n+1: -1/(2*A080277(n)-1); %e A118829 at k = 4*n+2: -1/(2*A080277(n)-2); %e A118829 at k = 4*n-1: 0. %e A118829 Convergents begin: %e A118829 1/1, -1/-2, 0/-1, -1/2, -1/1, 1/0, 0/1, 1/-8, %e A118829 1/-7, -1/6, 0/-1, -1/10, -1/9, 1/-8, 0/1, 1/-24, %e A118829 1/-23, -1/22, 0/-1, -1/26, -1/25, 1/-24, 0/1, 1/-32, %e A118829 1/-31, -1/30, 0/-1, -1/34, -1/33, 1/-32, 0/1, 1/-64, ... %o A118829 (PARI) {a(n)=local(p=+1,q=-2,v=vector(n,i,if(i%2==1,p,q*2^valuation(i/2,2)))); contfracpnqn(v)[1,1]} %Y A118829 Cf. A118827 (partial quotients), A118829 (denominators). %K A118829 frac,sign %O A118829 1,2 %A A118829 _Paul D. Hanna_, May 01 2006