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 A351557 #17 Feb 20 2022 11:00:20
%S A351557 1,3,2,1,2,3,2,1,1,3,6,7,14,3,6,1,2,3,2,1,2,3,6,1,1,21,2,7,10,3,2,1,2,
%T A351557 3,6,13,2,15,2,1,14,3,2,7,26,3,6,1,1,3,6,1,2,15,6,1,2,3,6,7,2,3,26,1,
%U A351557 2,3,34,1,2,3,6,1,2,3,2,35,2,21,10,1,11,3,6,1,2,33,30,1,2,3,14,7,2,3,30,1,2,3,78
%N A351557 a(n) = gcd(sigma(n), A019565(n)).
%H A351557 Antti Karttunen, <a href="/A351557/b351557.txt">Table of n, a(n) for n = 1..65537</a>
%H A351557 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%H A351557 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A351557 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A351557 a(n) = gcd(A000203(n), A019565(n)) = gcd(A080398(n), A019565(n)).
%F A351557 a(n) = A007947(a(n)).
%F A351557 a(n) = A019565(A351559(n)).
%t A351557 Table[GCD[DivisorSigma[1, n], Times @@ Prime@ Flatten@ Position[Reverse@ IntegerDigits[n, 2], 1]], {n, 99}] (* _Michael De Vlieger_, Feb 20 2022 *)
%o A351557 (PARI)
%o A351557 A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
%o A351557 A351557(n) = gcd(sigma(n), A019565(n));
%Y A351557 Cf. A000203, A007947, A019565, A080398.
%Y A351557 Cf. also A324644, A351549, A351556, A351559.
%K A351557 nonn
%O A351557 1,2
%A A351557 _Antti Karttunen_, Feb 19 2022