A271221 Smallest Fermat pseudoprime k to all bases b = 2, 3, 4, ..., n.

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, 252601, 252601, 252601, 252601, 252601

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 A367319

Adjacent sequences: A271218 A271219 A271220 * A271222 A271223 A271224

Keyword

nonn,changed

Author

Felix Fröhlich, Apr 02 2016

Extensions

Edited by Thomas Ordowski, Apr 29 2018

Corrected a typo within the initial terms by Jens Ahlström, Apr 23 2024

Status

approved