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 A306671 #14 Sep 08 2022 08:46:21 %S A306671 1,2,1,1,1,4,1,4,3,4,1,6,1,4,1,1,1,6,1,2,1,4,1,8,1,4,1,2,1,8,1,2,1,4, %T A306671 1,9,1,4,1,8,1,8,1,2,3,4,1,2,1,2,1,2,1,8,1,8,1,4,1,12,1,4,3,1,1,8,1,2, %U A306671 1,8,1,12,1,4,3,2,1,8,1,10,1,4,1,12,1,4 %N A306671 a(n) = gcd(tau(n), pod(n)) where tau(k) = the number of the divisors of k (A000005) and pod(k) = the product of the divisors of k (A007955). %C A306671 Sequence of the smallest numbers k such that a(k) = n: 1, 2, 9, 6, 400, 12, 3136, 24, 36, 80, 123904, 60, 692224, 448, 2025, 120, ... %H A306671 Antti Karttunen, <a href="/A306671/b306671.txt">Table of n, a(n) for n = 1..16384</a> %H A306671 Antti Karttunen, <a href="/A306671/a306671.txt">Data supplement: n, a(n) computed for n = 1..65537</a> %F A306671 a(n) = 1 for numbers in A046642. %F A306671 a(n) = tau(n) for numbers in A120736. %e A306671 For n=6: a(6) = gcd(tau(6), pod(6)) = gcd(4, 36) = 4. %o A306671 (Magma) [GCD(NumberOfDivisors(n), &*[d: d in Divisors(n)]): n in [1.. 100]] %o A306671 (PARI) a(n) = gcd(numdiv(n), vecprod(divisors(n))); \\ _Michel Marcus_, Mar 04 2019 %Y A306671 Cf. A000005, A007955, A009205, A046642. %K A306671 nonn %O A306671 1,2 %A A306671 _Jaroslav Krizek_, Mar 04 2019