2516581domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(n) = a(n-1) + a(n-2) + a(n-3) + 2*a(n-4) with a(0)=2, a(1)=1, a(2)=5, a(3)=10.at n=21A226309Prime numbersat n=184202