a(n) = (2*n+1)*5^(2*n+1).A072172a(n) = (2*n+1)*5^(2*n+1).Terms a(0) =5a(1) =375a(2) =15625a(3) =546875a(4) =17578125a(5) =537109375a(6) =15869140625a(7) =457763671875External referencesoeis: A072172