Smallest k such that 4^^n is not congruent to 4^^(n-1) mod k, where 4^^n denotes the power tower 4^4^...^4 (in which 4 appears n times).

A246492

Smallest k such that 4^^n is not congruent to 4^^(n-1) mod k, where 4^^n denotes the power tower 4^4^...^4 (in which 4 appears n times).

Terms

    a(0) =2a(1) =5a(2) =11a(3) =23a(4) =47a(5) =283a(6) =719a(7) =1439a(8) =2879a(9) =34549a(10) =138197a(11) =1266767a(12) =4782969a(13) =14348907

External references