a(n) is the conjectured highest power of n which has no four identical digits in succession.

Terms

a(0) =35864a(1) =19590a(2) =17932a(3) =14103a(4) =9702a(5) =10061a(6) =8892a(7) =9795a(8) =3a(9) =6889a(10) =8069a(11) =8742a(12) =6448a(13) =6553a(14) =8966a(15) =4594a(16) =6800a(17) =6670a(18) =3a(19) =4869a(20) =5061a(21) =5635a(22) =6001a(23) =3784a(24) =6450a(25) =6530a(26) =4631a(27) =4930a(28) =3a(29) =4777