50284273908domain: NAppears in sequencesa(n) = a(n-3) - 5*a(n-2) + 5*a(n-1), a(0) = 1, a(1) = 3, a(2) = 10.at n=19A102871Indices of centered triangular numbers (A005448) which are also hexagonal numbers (A000384).at n=9A254284