Partial sums of A002893 with A002893(0)=0.

Terms

a(0) =0a(1) =3a(2) =18a(3) =111a(4) =750a(5) =5403a(6) =40572a(7) =313407a(8) =2471166a(9) =19791003a(10) =160459068a(11) =1313922063a(12) =10847561088a(13) =90174127683a(14) =754009158018