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The number 2 (that is, 1+1) in the Witt vector ring for p=2 over the integers.
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%I #6 Sep 24 2013 20:51:06

%S 2,-1,-4,-40,-4960,-147166720,-299211527038566400,

%T -2703337074029927682081937523621232640

%N The number 2 (that is, 1+1) in the Witt vector ring for p=2 over the integers.

%D Jean-Pierre Serre, Local Fields (Corps Locaux), chapter 2, paragraph 6

%F Sum(2^j*a(j)^(2^(i-j)), j=0..i)=2 for all i.

%e a(0)^4 + 2*a(1)^2 + 4*a(2) = 2^4 + 2*(-1)^2 + 4*(-4) = 16+2-16 = 2.

%Y Cf. A006173 and others.

%K sign

%O 0,1

%A _David A. Madore_, Jun 15 2001