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 A381204 #13 Feb 21 2025 16:46:51
%S A381204 1,1,2,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,
%T A381204 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,
%U A381204 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
%N A381204 a(n) is the gcd of the elements of the set of bases and exponents in the prime factorization of n.
%C A381204 The positions of terms > 1 are given by A368107.
%H A381204 Paolo Xausa, <a href="/A381204/b381204.txt">Table of n, a(n) for n = 2..10000</a>
%e A381204 a(16) = 2 because 16 = 2^4, the set of these bases and exponents is {2, 4} and gcd(2, 4) = 2.
%e A381204 a(19683) = 3 because 19683 = 3^9, the set of these bases and exponents is {3, 9} and gcd(3, 9) = 3.
%t A381204 A381204[n_] := GCD @@ Flatten[FactorInteger[n]];
%t A381204 Array[A381204, 100 ,2]
%o A381204 (PARI) a(n) = my(f=factor(n)); gcd(setunion(Set(f[,1]), Set(f[,2]))); \\ _Michel Marcus_, Feb 18 2025
%Y A381204 Cf. A368107, A381201, A381202, A381203, A381205.
%K A381204 nonn,easy
%O A381204 2,3
%A A381204 _Paolo Xausa_, Feb 17 2025