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A028312
Odd numbers k such that {1..k-1} cannot be partitioned into disjoint sets I, J such that 2I == -J (mod k) and I, J are unions of cyclotomic cosets mod k.
1
3, 9, 11, 15, 19, 21, 27, 33, 39, 43, 45, 51, 55, 57, 59
OFFSET
1,1
LINKS
F. J. MacWilliams, A. M. Odlyzko, N. J. A. Sloane and H. N. Ward, Self-Dual Codes over GF(4), J. Combin. Theory, A 25 288-318 1978.
CROSSREFS
Cf. A028311.
Sequence in context: A190226 A059326 A370873 * A310315 A074486 A131861
KEYWORD
nonn,more
EXTENSIONS
a(10)-a(15) from Sean A. Irvine, Jan 11 2020
STATUS
approved