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 A366967 #12 Oct 30 2023 13:11:12
%S A366967 0,1,4,11,21,40,61,96,135,191,246,337,415,528,646,801,937,1145,1316,
%T A366967 1568,1802,2089,2342,2737,3047,3451,3841,4338,4744,5358,5823,6474,
%U A366967 7060,7758,8384,9294,9960,10835,11657,12717,13537,14739,15642,16881,18025,19314,20395
%N A366967 a(n) = Sum_{k=2..n} binomial(k,2) * floor(n/k).
%F A366967 G.f.: 1/(1-x) * Sum_{k>=1} x^(2*k)/(1-x^k)^3 = 1/(1-x) * Sum_{k>=2} binomial(k,2) * x^k/(1-x^k).
%F A366967 a(n) = (A064602(n)-A024916(n))/2. - _Chai Wah Wu_, Oct 30 2023
%o A366967 (PARI) a(n) = sum(k=2, n, binomial(k, 2)*(n\k));
%o A366967 (Python)
%o A366967 from math import isqrt
%o A366967 def A366967(n): return ((s:=isqrt(n))**2*(1-s**2)+sum((q:=n//k)*(3*k*(k-1)+q**2-1) for k in range(1,s+1)))//6 # _Chai Wah Wu_, Oct 30 2023
%Y A366967 Partial sums of A069153.
%Y A366967 Cf. A002541, A236632.
%Y A366967 Cf. A024916, A064602, A366971.
%K A366967 nonn
%O A366967 1,3
%A A366967 _Seiichi Manyama_, Oct 30 2023