[seqfan] Re: A178705
Fred Lunnon
fred.lunnon at gmail.com
Wed Dec 20 06:57:25 CET 2017
Wikipedia appears to agree about missing entries:
https://en.wikipedia.org/wiki/Strong_pseudoprime
WFL
On 12/20/17, israel at math.ubc.ca <israel at math.ubc.ca> wrote:
> A178705 is "Numbers q that are strong pseudoprimes to some base a,
> 2<=a<=q-2, such that a^d == 1 mod q"
>
> which I interpret as: odd composite numbers q such that there exists a,
> 2<=a<=q-2, such that a^d == 1 mod q where d = A000265(q-1).
>
> However, the Data seem to be missing quite a few such numbers:
>
> 91, 175, 231, 247, 259, 341, 343, 403, 427, 435, 451, 475, 511, 559, 595,
> 651, 671, 679, 703, 715, 763, 775, 847, 871, 891, 931, 949, 1015, 1027,
> 1035, 1075, 1099, 1111, 1147, 1159, 1183, 1247, 1267, 1271, 1331, 1339,
> 1351, 1387, 1431, 1435, 1491, 1495
>
> For example, 91 should be there because 9^45 == 1 (mod 91), and 175 should
> be there because 51^87 = 1 mod 175.
>
> Am I misinterpreting the definition? Is there some reasonable way to define
> a sequence with the given Data? Or should the missing numbers be inserted?
>
> Cheers,
> Robert
>
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