New extremal self-dual codes of length 62 and related extremal self-dual codes

In this correspondence, new extremal self-dual codes of length 62 are constructed with weight enumerators of three different types. Two of these types were not represented by any known code up till now. All these codes possess an automorphism of order 15. Some of them are used to construct extremal self-dual codes of length 60 by the method of subtracting. Manuscript received November 20, 2001; revised January 12, 2002. This work was supported in part by Shumen University under Grant N5/08.05.2001. R. Dontcheva is with the Faculty of Information Technology and Systems, Delft University of Technology, 2628 CD Delft, The Netherlands, on leave from the University of Shumen, Bulgaria. M. Harada is with the Department of Mathematical Sciences, Yamagata University, Yamagata 990-8560, Japan. Communicated by P. Solé, Associate Editor for Coding Theory. Publisher Item Identifier S 0018-9448(02)05334-8. By additional subtracting, an extremal self-dual [58 29 10] code was obtained having a weight enumerator which does not correspond to any code known so far.