Wieferich pairs and Barker sequences, II
Wieferich pairs and Barker sequences, II
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维弗里希对和巴克序列,II
DOI:
10.1112/s1461157013000223
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发表时间:
2013
期刊:
影响因子:
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通讯作者:
Michael J. Mossinghoff
中科院分区:
文献类型:
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作者:
P. Borwein;Michael J. Mossinghoff
We show that if a Barker sequence of length $n>13$
exists, then either n $=$
3 979 201 339 721 749 133 016 171 583 224 100, or $n > 4\cdot 10^{33}$
. This improves the lower bound on the length of a long Barker sequence by a factor of nearly $2000$
. We also obtain eighteen additional integers $n<10^{50}$
that cannot be ruled out as the length of a Barker sequence, and find more than 237 000 additional candidates $n<10^{100}$
. These results are obtained by completing extensive searches for Wieferich prime pairs and using them, together with a number of arithmetic restrictions on $n$
, to construct qualifying integers below a given bound. We also report on some updated computations regarding open cases of the circulant Hadamard matrix problem.