a(n) = (7*n+1) * (8*n+1)^(n-2) * 9^n.A251699a(n) = (7*n+1) * (8*n+1)^(n-2) * 9^n.Terms a(0) =1a(1) =8a(2) =1215a(3) =400950a(4) =207202941a(5) =146509780644External referencesoeis: A251699