A114249 Number of Fermat pseudoprimes to base 7 less than 10^n.

1, 2, 6, 16, 73, 234, 659, 1797, 4950, 13070, 33989, 87448

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Eric Weisstein's World of Mathematics, Fermat Pseudoprime

Mathematica

Table[Count[Select[Range[2, 10^6], ! PrimeQ[#] && PowerMod[7, # - 1, #] == 1 &], x_ /; x < 10^n], {n, 6}]  (* Robert Price, Jun 09 2019 *)

Crossrefs

Cf. A005938, A055550, A114245, A114247.

Sequence in context: A009328 A009346 A009367 * A147910 A147902 A147893

Adjacent sequences: A114246 A114247 A114248 * A114250 A114251 A114252

Keyword

nonn,more

Author

Eric W. Weisstein, Nov 18 2005

Extensions

a(9)-a(12) from Hiroaki Yamanouchi, Sep 25 2015

Status

approved