This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A381538 #19 Mar 09 2025 13:09:49 %S A381538 1,4,16,27,256,3125,19683,46656,65536,823543,16777216,387420489, %T A381538 4294967296,10000000000,285311670611,7625597484987,8916100448256, %U A381538 302875106592253,11112006825558016,298023223876953125,437893890380859375,18446744073709551616 %N A381538 Numbers of the form m^(m^k). %e A381538 27 = 3^(3^1) -> a(4). %e A381538 256 = 2^(2^3) = 4^(4^1) -> a(5). %o A381538 (PARI) upto(limit)=my(L=List([1])); for(m=2, oo, my(t=logint(limit,m)); if(t<m, return(Set(L))); for(k=1, logint(t,m), listput(L,m^(m^k)))) \\ _Andrew Howroyd_, Feb 26 2025 %Y A381538 Subsequence of A001597; supersequence of A000312 (apart from initial term), A097374, and A257309 (apart from initial term). %Y A381538 Subset of A380760 for a(n)>=16, and of A067688 for prime m. %K A381538 nonn %O A381538 1,2 %A A381538 _Charles L. Hohn_, Feb 26 2025