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 A061655 #6 Sep 24 2013 20:51:06 %S A061655 2,-1,-4,-40,-4960,-147166720,-299211527038566400, %T A061655 -2703337074029927682081937523621232640 %N A061655 The number 2 (that is, 1+1) in the Witt vector ring for p=2 over the integers. %D A061655 Jean-Pierre Serre, Local Fields (Corps Locaux), chapter 2, paragraph 6 %F A061655 Sum(2^j*a(j)^(2^(i-j)), j=0..i)=2 for all i. %e A061655 a(0)^4 + 2*a(1)^2 + 4*a(2) = 2^4 + 2*(-1)^2 + 4*(-4) = 16+2-16 = 2. %Y A061655 Cf. A006173 and others. %K A061655 sign %O A061655 0,1 %A A061655 _David A. Madore_, Jun 15 2001