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 A145607 #19 Apr 25 2024 09:19:24 %S A145607 0,4,35,279,2200,17324,136395,1073839,8454320,66560724,524031475, %T A145607 4125691079,32481497160,255726286204,2013328792475,15850904053599, %U A145607 124793903636320,982500325036964,7735208696659395,60899169248238199 %N A145607 Numbers k such that (3*(2*k + 1)^2 + 2)/5 is a square. %C A145607 Square roots of (3*(2*k+1)^2+2)/5 are listed in A070997, therefore (3*(2*a(n) + 1)^2 + 2)/5 = A070997(n-1)^2. %H A145607 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-9,1). %F A145607 a(n+2) = 8*a(n+1) - a(n) + 3. %F A145607 From _R. J. Mathar_, Oct 24 2008: (Start) %F A145607 G.f.: x^2*(4 - x)/((1 - x)*(1 - 8*x + x^2)). %F A145607 a(n) = (A057080(n-1)-1)/2. (End) %Y A145607 Cf. A070997, A131751. %Y A145607 Cf. A001091 (first differences). %K A145607 nonn,easy %O A145607 1,2 %A A145607 _Richard Choulet_, Oct 14 2008 %E A145607 a(4) corrected, extended, definition corrected by _R. J. Mathar_, Oct 24 2008 %E A145607 Offset changed by _Bruno Berselli_, Apr 06 2018