A391882 a(n) is the least k > 0 such that n! + k is an odd nonsquare semiprime (A046388).

14, 14, 13, 9, 9, 3, 1, 5, 1, 5, 1, 3, 17, 1, 1, 7, 7, 3, 23, 1, 1, 11, 29, 3, 1, 1, 1, 37, 1, 41, 47, 19, 11, 11, 1, 7, 3, 41, 1, 13, 127, 47, 59, 17, 37, 5, 37, 59, 1, 61, 73, 59, 79, 73, 1, 1, 61, 149, 37, 1, 61, 31, 37, 43, 7, 83, 71, 19, 7, 103, 19, 1, 107, 37

Offset

0,1

Links

Table of n, a(n) for n=0..73.

Prog

(PARI) a391882(n) = my(nf=n!); for(k=1, oo, my(m=nf+k); if(m%2, my(f=factor(m)); if(omega(f)==2 && bigomega(f)==2, return(k))))

Crossrefs

Cf. A046388, A131057, A356207.

Sequence in context: A199256 A199201 A128883 * A010853 A291510 A186128

Adjacent sequences: A391879 A391880 A391881 * A391883 A391884 A391885

Keyword

nonn

Author

Hugo Pfoertner, Dec 30 2025

Status

approved