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A271221 Smallest Fermat pseudoprime k to all bases b = 2, 3, 4, ..., n. 3
341, 1105, 1105, 1729, 1729, 29341, 29341, 29341, 29341, 29341, 29341, 162401, 162401, 162401, 162401, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 252601, 251601, 252601, 252601, 252601, 252601 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

a(n) is the smallest composite k such that b^(k-1) == 1 (mod (b-1)k) for every b = 2, 3, 4, ..., n. For more comments, see A083876 and A300629. - Max Alekseyev and Thomas Ordowski, Apr 29 2018

LINKS

Table of n, a(n) for n=2..40.

PROG

(PARI) a(n) = forcomposite(c=1, , my(i=0); for(b=2, n, if(Mod(b, c)^(c-1)==1, i++)); if(i==n-1, return(c)));

CROSSREFS

Cf. A052155, A083737, A083739, A083876, A300629.

Sequence in context: A179839 A172255 A087835 * A066488 A291601 A083876

Adjacent sequences:  A271218 A271219 A271220 * A271222 A271223 A271224

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Apr 02 2016

EXTENSIONS

Edited by Thomas Ordowski, Apr 29 2018

STATUS

approved

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Last modified December 8 01:34 EST 2019. Contains 329850 sequences. (Running on oeis4.)