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A082952 Smaller of the two factors of the n-th semiprime number of the form m!+1. 3

%I #8 Dec 11 2023 17:32:25

%S 5,11,7,71,61,11,83,23,71,20639383,811,401,1697,29,67411,

%T 14029308060317546154181,12893,12318573951317236818169524329,79,16567,

%U 6653,293,229758023927584562777368125832724248866067995638905559798117

%N Smaller of the two factors of the n-th semiprime number of the form m!+1.

%H Paul Leyland, <a href="http://www.leyland.vispa.com/numth/factorization/main.htm">Tables of factors of N!+1 and N!-1.</a>

%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha104.htm">n! + 1 (n = 1 to 100).</a>

%F Numbers p such that p*q=A078778(n)!+1, p, q prime, p<q

%e a(3)=7 because A078778(3)!+1=6!+1=721=7*103

%t FactorInteger[#][[1,1]]&/@Select[Range[50]!+1,PrimeOmega[#]==2&] (* The program generates the first 17 terms of the sequence. To generate more, increase the Range constant but the program may take a long time to run.*) (* _Harvey P. Dale_, Dec 11 2023 *)

%Y Cf. A046315, A078778, A002981, A080802.

%K nonn

%O 1,1

%A _Hugo Pfoertner_, May 26 2003

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Last modified March 28 13:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)