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 A185542 #13 Feb 27 2024 19:16:12
%S A185542 1,15,120,528,1540,3916,8385,16471,29646,50086,80601,124251,185745,
%T A185542 269011,379756,524800,709836,944625,1237951,1599366,2041210,2577585,
%U A185542 3216916,3980431,4884375,5939181,7172578,8605026,10253656,12149985,14313925,16776528,19565640,22717170,26263128,30236976,34673628
%N A185542 a(n) = m*(m+1)/2, where m = floor(n^(5/2)).
%C A185542 A subsequence of A000217, the triangular numbers.
%H A185542 G. C. Greubel, <a href="/A185542/b185542.txt">Table of n, a(n) for n = 1..5000</a>
%F A185542 a(n) = A000217(A155013(n)). - _Michel Marcus_, Jul 08 2017
%t A185542 f[n_] = Floor[n^(5/2)]*Floor[n^(5/2)+1]/2; Table[f[n],{n,1,80}]
%t A185542 (#(#+1))/2&/@Floor[Range[40]^(5/2)] (* _Harvey P. Dale_, Feb 27 2024 *)
%o A185542 (PARI) for(n=1,50, print1(floor(n^(5/2))*floor(1 + n^(5/2))/2, ", ")) \\ _G. C. Greubel_, Jul 07 2017
%Y A185542 Cf. A000217, A155013.
%K A185542 nonn
%O A185542 1,2
%A A185542 _Clark Kimberling_, Jan 30 2011