83478domain: NAppears in sequencesa(n) = Sum{T(i,j)}, 0<=j<=i, 0<=i<=n, T given by A026568.at n=12A026582Number x = concat(MSD(x),b) such that MSD(x)*b = phi(x), where MSD(x) is the Most Significant Digit of x and phi(x) is the Euler totient function of x.at n=37A286130