45669domain: NAppears in sequencesa(0) = 0, a(1) = a(2) = 1, a(3) = 2, a(4) = 4, for n>3: a(n+1) = SORT[ a(n) + a(n-1) + a(n-2) + a(n-3) + a(n-4)], where SORT places digits in ascending order and deletes 0's.at n=45A108565Number of cusps in a class of degree-3n complex algebraic surfaces.at n=19A225018