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 A343565 #24 May 25 2021 09:18:50
%S A343565 1,2,9,30,125,428,1715,6270,24255,91367,352715,1345448,5200299,
%T A343565 20019526,77554749,300295038,1166803109,4535971916,17672631899,
%U A343565 68913247655,269128640958,1051984969598,4116715363799,16123381989000,63205303195125,247956558998878,973469689288236
%N A343565 a(n) = |{(x_1, x_2, ... , x_n) : 1 <= x_1 <= x_2 <= ... <= x_n <= n, gcd(x_1, x_2, ... , x_n, n) = 1}|.
%H A343565 Seiichi Manyama, <a href="/A343565/b343565.txt">Table of n, a(n) for n = 1..1000</a>
%F A343565 a(n) = Sum_{d|n} mu(n/d) * binomial(d+n-1, n).
%F A343565 a(n) = [x^n] Sum_{k>=1} mu(k) * x^k/(1 - x^k)^(n+1).
%t A343565 a[n_] := DivisorSum[n, MoebiusMu[n/#] * Binomial[# + n - 1, n] &]; Array[a, 30] (* _Amiram Eldar_, Apr 25 2021 *)
%o A343565 (PARI) a(n) = sumdiv(n, d, moebius(n/d)*binomial(d+n-1, n));
%Y A343565 Cf. A000010, A007438, A117108, A117109, A332470, A343517, A343548, A343549.
%K A343565 nonn
%O A343565 1,2
%A A343565 _Seiichi Manyama_, Apr 20 2021