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 A343549 #23 Jun 14 2023 10:37:05
%S A343549 1,5,13,49,131,545,1723,6809,24484,94445,352727,1366273,5200313,
%T A343549 20135939,77571083,301034537,1166803127,4540794476,17672631919,
%U A343549 68943346009,269129827042,1052178506615,4116715363823,16124644677569,63205303337656,247964681424725,973469783435197
%N A343549 a(n) = n * Sum_{d|n} binomial(d+n-1,n)/d.
%H A343549 Seiichi Manyama, <a href="/A343549/b343549.txt">Table of n, a(n) for n = 1..1000</a>
%F A343549 a(n) = [x^n] Sum_{k>=1} k * x^k/(1 - x^k)^(n+1).
%F A343549 a(n) = [x^n] Sum_{k>=1} binomial(k+n-1,n) * x^k/(1 - x^k)^2.
%F A343549 From _Seiichi Manyama_, Jun 14 2023: (Start)
%F A343549 a(n) = Sum_{d|n} binomial(d+n-1,d).
%F A343549 a(n) = [x^n] Sum_{k>=1} (1/(1 - x^k)^n - 1). (End)
%t A343549 a[n_] := n * DivisorSum[n, Binomial[# + n - 1, n]/# &]; Array[a, 30] (* _Amiram Eldar_, Apr 25 2021 *)
%o A343549 (PARI) a(n) = n*sumdiv(n, d, binomial(d+n-1, n)/d);
%Y A343549 Cf. A000203, A038040, A309731, A343544, A343545, A343546, A343547, A343548.
%K A343549 nonn
%O A343549 1,2
%A A343549 _Seiichi Manyama_, Apr 19 2021