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 A331290 #10 Jan 15 2020 18:40:19 %S A331290 1,1,1,2,1,2,1,1,1,2,1,1,1,2,2,2,1,1,1,1,2,2,1,1,2,2,1,1,1,1,1,1,2,2, %T A331290 2,4,1,2,2,1,1,1,1,1,1,2,1,1,1,1,2,1,1,2,2,4,2,2,1,1,1,2,3,2,1,3,1,1, %U A331290 2,1,1,1,1,2,1,1,2,3,1,1,1,2,1,2,1,2,2,4,1,2,2,1,2,2,1,2,1,1,1,1,1,3,1,4,1 %N A331290 a(n) = gcd(A001222(n), A329348(n)). %C A331290 Records occur at n = 1, 4, 36, 112, 352, 1088, 2016, 2688, 8064, 63360, ... %H A331290 Antti Karttunen, <a href="/A331290/b331290.txt">Table of n, a(n) for n = 1..65537</a> %H A331290 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a> %H A331290 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a> %H A331290 <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a> %F A331290 a(n) = gcd(A001222(n), A329348(n)) = gcd(A001222(n), A331188(n) mod A117366(n)). %F A331290 a(n) = gcd(A001222(n), A331289(n)). %o A331290 (PARI) %o A331290 A002110(n) = prod(i=1, n, prime(i)); %o A331290 A331290(n) = if(1==n, 1, my(f=factor(n), p=nextprime(1+vecmax(f[, 1]))); gcd((prod(i=1, #f~, A002110(primepi(f[i, 1]))^(f[i, 2]-(#f~==i)))%p),bigomega(n))); %Y A331290 Cf. A001222, A002110, A117366, A329348, A331188, A331289, A331291. %Y A331290 Cf. also A329618, A329621. %K A331290 nonn,less %O A331290 1,4 %A A331290 _Antti Karttunen_, Jan 15 2020