267795domain: NAppears in sequencesa(n) equals the (n*(n+1)/2)-th partial sum of the self-convolution 4th power of A010054, which has the g.f.: Sum_{k>=0} x^(k*(k+1)/2).at n=30A109415Number of permutations of n distinct letters (ABCD...) each of which appears thrice with n-4 fixed points.at n=9A124008