48888888889domain: NAppears in sequencesPrimes of the form (44*10^n+1)/9.at n=4A177503Smallest prime with n holes in its decimal digits.at n=20A327820Expansion of (1 + 4*x - 6*x^2) / ((1 - x) * (1 - 10*x^2)).at n=21A328333The smallest prime number with exactly n circular loops in its decimal representation.at n=19A331898