A114247 - OEIS

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A114247

Number of Fermat pseudoprimes to base 5 less than 10^n.

6

1, 1, 5, 20, 73, 248, 745, 1954, 5239, 13837, 36042, 92893

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

LINKS

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

Eric Weisstein's World of Mathematics, Fermat Pseudoprime

Index entries for sequences related to pseudoprimes

MATHEMATICA

Table[Count[Select[Range[2, 10^6], ! PrimeQ[#] && PowerMod[5, # - 1, #] == 1 &], x_ /; x < 10^n], {n, 6}] (* Robert Price, Jun 09 2019 *)

CROSSREFS

Cf. A005936, A114245, A114249.

Sequence in context: A270080 A271136 A118049 * A272086 A006650 A034535

Adjacent sequences: A114244 A114245 A114246 * A114248 A114249 A114250

KEYWORD

nonn,more

AUTHOR

Eric W. Weisstein, Nov 18 2005

EXTENSIONS

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

STATUS

approved