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 A122656 #28 May 15 2024 01:31:20
%S A122656 0,0,2,3,16,20,54,63,128,144,250,275,432,468,686,735,1024,1088,1458,
%T A122656 1539,2000,2100,2662,2783,3456,3600,4394,4563,5488,5684,6750,6975,
%U A122656 8192,8448,9826,10115,11664,11988,13718,14079,16000,16400,18522,18963,21296,21780
%N A122656 a(n) = n*floor(n/2)^2.
%C A122656 Szeged index of cycle of length n.
%H A122656 Vincenzo Librandi, <a href="/A122656/b122656.txt">Table of n, a(n) for n = 0..1000</a>
%H A122656 Janez Žerovnik, <a href="https://doi.org/10.1021/ci980148q">Szeged index of symmetric graphs</a>, J. Chem. Inf. Comput. Sci., 39 (1999), 77-80; <a href="https://scholar.archive.org/work/mjwr5vqtzjhwzlnmlpfuzsy4oq/access/wayback/http://home.postech.ac.kr:80/~arang/JCICS/1999/No.1/77.pdf">alternative link</a>.
%H A122656 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,3,-3,-3,3,1,-1).
%F A122656 a(n) = (n*(1-(-1)^n+2*(-1+(-1)^n)*n+2*n^2))/8. G.f.: x^2*(x^4+x^3+7*x^2+x+2) / ((x-1)^4*(x+1)^3). - _Colin Barker_, Sep 20 2013
%F A122656 a(n) = n*A008794(n). - _R. J. Mathar_, Mar 04 2018
%F A122656 Sum_{n>=2} 1/a(n) = zeta(3)/2 + zeta(2) + 4*(log(2)-1). - _Amiram Eldar_, May 15 2024
%t A122656 Table[n Floor[n/2]^2,{n,0,50}] (* or *) LinearRecurrence[ {1,3,-3,-3,3,1,-1},{0,0,2,3,16,20,54},50] (* _Harvey P. Dale_, May 31 2014 *)
%o A122656 (Magma) [n*Floor(n/2)^2: n in [0..50]]; // _Vincenzo Librandi_, May 31 2014
%Y A122656 Cf. A002117, A013661, A008794.
%K A122656 nonn,easy
%O A122656 0,3
%A A122656 _N. J. A. Sloane_, Sep 22 2006