3601659604domain: NAppears in sequencesa(n) = 8*a(n-1) - a(n-2); a(0) = 1, a(1) = 4.at n=11A001091Numerators of continued fraction convergents to sqrt(15).at n=21A041022a(n)*a(n+3) - a(n+1)*a(n+2) = 3, given a(0)=a(1)=1, a(2)=4.at n=22A080871Denominators in continued fraction expansion of sqrt(3/5).at n=21A145543