OFFSET
1,1
LINKS
Hugo Pfoertner, Table of n, a(n) for n = 1..17
Andrew Walker, Table of factors of (n!)^2+1.
FORMULA
Numbers p such that p*q = (A083340(n)!)^2 + 1, p, q prime, p < q.
EXAMPLE
PROG
(PARI) for(n=1, 29, my(f=(n!)^2+1); if(bigomega(f)==2, print1(vecmin(factor(f)[, 1]), ", "))) \\ Hugo Pfoertner, Jul 13 2019
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Hugo Pfoertner, Apr 25 2003
EXTENSIONS
The 11th term of the sequence (49-digit factor of the 100-digit number (41!)^2+1) was found with Yuji Kida's multiple polynomial quadratic sieve UBASIC PPMPQS v3.5 in 13 days CPU time on an Intel PIII 550 MHz.
Missing a(4) and new a(14), a(15) added by Hugo Pfoertner, Jul 13 2019
STATUS
approved