a(1)=1; a(n) = gcd(a(n-1), n) + lcm(a(n-1), n).

Terms

a(0) =1a(1) =3a(2) =6a(3) =14a(4) =71a(5) =427a(6) =434a(7) =1738a(8) =15643a(9) =156431a(10) =156442a(11) =938654a(12) =12202503a(13) =170835043a(14) =2562525646a(15) =20500205170a(16) =348503487891