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 A165743 #15 Sep 16 2023 05:30:48
%S A165743 1,2,3,2,5,6,7,2,3,10,1,6,1,14,15,2,1,6,1,10,21,2,1,6,5,2,3,14,1,30,1,
%T A165743 2,3,2,35,6,1,2,3,10,1,42,1,2,15,2,1,6,7,10,3,2,1,6,5,14,3,2,1,30,1,2,
%U A165743 21,2,5,6,1,2,3,70,1,6,1,2,15,2,7,6,1,10,3,2,1,42,5,2,3,2,1,30,7,2,3,2,5,6
%N A165743 The greatest common divisor of n and 210.
%C A165743 Note: 210 = 2*3*5*7, the product of the first four primes.
%C A165743 gcd(n,2*3) is A089128; gcd(n,2*3*5) not currently in the OEIS. - _R. J. Mathar_, Feb 07 2011
%F A165743 From _Amiram Eldar_, Sep 16 2023: (Start)
%F A165743 a(n) = gcd(n, 210).
%F A165743 Multiplicative with a(p^e) = p if p <= 7, and 1 otherwise.
%F A165743 Dirichlet g.f.: zeta(s) * (1 + 1/2^s) * (1 + 2/3^s) * (1 + 4/5^s) * (1 + 6/7^s).
%F A165743 Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 117/14. (End)
%p A165743 seq(gcd(n, 210), n = 1 .. 100); # _Emeric Deutsch_, Oct 31 2009
%t A165743 a[n_] := GCD[n, 210]; Array[a, 100] (* _Amiram Eldar_, Sep 16 2023 *)
%o A165743 (PARI) a(n) = gcd(n, 210); \\ _Amiram Eldar_, Sep 16 2023
%Y A165743 Cf. A089128.
%K A165743 nonn,easy,mult
%O A165743 1,2
%A A165743 Mick Purcell (mickpurcell(AT)gmail.com), Sep 26 2009
%E A165743 Extended by _Emeric Deutsch_, Oct 31 2009