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 A072818 #17 Jan 01 2024 11:04:54 %S A072818 0,20,1960,192060,18819920,1844160100,180708869880,17707625088140, %T A072818 1735166549767840,170028614252160180,16661069030161929800, %U A072818 1632614736341616960220,159979583092448300171760 %N A072818 Possibly the only integers of the form sqrt(m^2*(m^2-1)*2/3) [only checked for the first 5 terms]. %C A072818 These are the standard deviations of time for a random walk starting at 0 to reach one of the boundaries at +A001079(n) or -A001079(n) for the first time. %H A072818 Indranil Ghosh, <a href="/A072818/b072818.txt">Table of n, a(n) for n = 0..501</a> %H A072818 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a> %H A072818 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (98, -1). %F A072818 a(n) = 98*a(n-1)-a(n-2) [starting with a(0)=0 and a(1)=20] =sqrt(A072819(A001079(n))). %F A072818 G.f.: 20x/(1-98x+x^2). [_Philippe Deléham_, Nov 18 2008] %e A072818 0 and 20 are at the start of the sequence since m^2*(m^2-1)*2/3 (A072819) starts 0, 0, 8, 48, 160, 400, 840, 1568, ... and the only squares among these are 0 and 400 with square roots of 0 and 20. %K A072818 nonn %O A072818 0,2 %A A072818 _Henry Bottomley_, Jul 14 2002