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

5, 11, 7, 71, 61, 11, 83, 23, 71, 20639383, 811, 401, 1697, 29, 67411, 14029308060317546154181, 12893, 12318573951317236818169524329, 79, 16567, 6653, 293, 229758023927584562777368125832724248866067995638905559798117

Offset

1,1

Links

Table of n, a(n) for n=1..23.

Paul Leyland, Tables of factors of N!+1 and N!-1.

Hisanori Mishima, n! + 1 (n = 1 to 100).

Formula

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

Example

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

Mathematica

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 *)

Crossrefs

Cf. A046315, A078778, A002981, A080802.

Sequence in context: A358613 A329005 A290195 * A113964 A356480 A075261

Adjacent sequences: A082949 A082950 A082951 * A082953 A082954 A082955

Keyword

nonn

Author

Hugo Pfoertner, May 26 2003

Status

approved