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A267288 Composites c where at least one base b with 1 < b < c exists such that b^(c-1) == 1 (mod c^2), i.e., composites c that are base-b 'Wieferich pseudoprimes' for at least one b between 1 and c. 4
133, 451, 561, 871, 904, 1065, 1105, 1267, 1729, 1891, 2059, 2201, 2501, 2821, 2993, 3145, 4641, 5005, 5551, 5841, 5963, 6409, 6541, 6601, 6697, 7107, 7471, 7501, 8321, 8323, 9637, 10585, 11266, 12209, 12403, 13571, 13585, 16471, 17261, 17466, 17770, 18103 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A002808(i) such that A256517(i) < A002808(i).

Any term is also a term of A039769.

LINKS

Table of n, a(n) for n=1..42.

EXAMPLE

871 is a term of the sequence, since 699^870 == 1 (mod 871^2) and 699 < 871.

PROG

(PARI) forcomposite(c=2, , for(b=2, c-1, if(Mod(b, c^2)^(c-1)==1, print1(c, ", "); break({1}))))

CROSSREFS

Cf. A039769, A134307, A255885, A256517.

Sequence in context: A070158 A055940 A251131 * A334037 A137879 A249108

Adjacent sequences:  A267285 A267286 A267287 * A267289 A267290 A267291

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Jan 12 2016

STATUS

approved

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Last modified September 19 14:14 EDT 2020. Contains 337178 sequences. (Running on oeis4.)