1914791domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(n) is the least k such that n*k-1 has exactly n prime factors, counted with multiplicity.at n=22A366857a(n) is the largest prime factor of n*2^n+1 for n>0, and a(0)=1.at n=21A367005Prime numbersat n=143058