a(n) = n^n*(3+n)/2.A174962a(n) = n^n*(3+n)/2.Terms a(0) =2a(1) =10a(2) =81a(3) =896a(4) =12500a(5) =209952a(6) =4117715a(7) =92274688a(8) =2324522934a(9) =65000000000External referencesoeis: A174962