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 A235711 #16 Apr 11 2025 03:26:41 %S A235711 0,0,0,1,4,5,6,16,32,24,10,31,60,41,14,92,192,156,108,123,140,87,22, %T A235711 188,384,220,26,131,252,247,240,608,1024,560,34,375,756,417,38,476, %U A235711 960,704,420,493,572,321,46,1036,2112,1340,500,635,780,1107,1458,1620 %N A235711 Arithmetic derivative of quarter squares. %H A235711 Reinhard Zumkeller, <a href="/A235711/b235711.txt">Table of n, a(n) for n = 0..10000</a> %F A235711 a(n) = A003415(A002620(n)); %F A235711 a(2*n) = A068720(n), n > 0. %t A235711 ad[n_] := n * Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); ad[0] = ad[1] = 0; a[n_] := ad[Floor[n^2/4]]; Array[a, 100, 0] (* _Amiram Eldar_, Apr 11 2025 *) %o A235711 (Haskell) %o A235711 a235711 = a003415 . a002620 %Y A235711 Cf. A002620, A003415, A068720. %K A235711 nonn,easy %O A235711 0,5 %A A235711 _Reinhard Zumkeller_, Mar 18 2014