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A271221 Smallest Fermat pseudoprime k to all bases b = 2, 3, 4, ..., n. 6

%I #28 May 15 2018 04:52:00

%S 341,1105,1105,1729,1729,29341,29341,29341,29341,29341,29341,162401,

%T 162401,162401,162401,252601,252601,252601,252601,252601,252601,

%U 252601,252601,252601,252601,252601,252601,252601,252601,252601,252601,252601,252601,252601,251601,252601,252601,252601,252601

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

%C 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

%o (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)));

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

%K nonn

%O 2,1

%A _Felix Fröhlich_, Apr 02 2016

%E Edited by _Thomas Ordowski_, Apr 29 2018

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Last modified April 24 12:22 EDT 2024. Contains 371937 sequences. (Running on oeis4.)