a(n) = 4*3^(n^2+2n+1)*Product_{j=1..n} (9^j-1).A092299a(n) = 4*3^(n^2+2n+1)*Product_{j=1..n} (9^j-1).Terms a(0) =12a(1) =2592a(2) =50388480External referencesoeis: A092299