Slowest increasing sequence beginning with 3 whose digits satisfy the rule d*2.

Terms

a(0) =3a(1) =6a(2) =12a(3) =24a(4) =48a(5) =81a(6) =616a(7) =2122a(8) =12424a(9) =42484a(10) =88481a(11) =681616a(12) =816212a(13) =1621221a(14) =2162124a(15) =2421242a(16) =4424212a(17) =42484842a(18) =48488484a(19) =248481681a(20) =684816816a(21) =1681684816a(22) =8162121621a(23) =21681621216a(24) =212212162121a(25) =681621216212