On a class of self-dual codes derived from quadratic residues
Thomas Aaron Gulliver, Nikolai Senkevitch · IEEE Transactions on Information Theory · 1999
In 1976, Moore investigated a class of self-dual double-circulant codes based on primes of the form q=3 mod 8. This paper shows that the corresponding length 168 code contains a weight 28 codeword and thus is not extremal. This answers a long-standing question regarding this code. The next five codes in this class are also shown not to be extremal.