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 A113338 #18 Jan 13 2025 12:28:10 %S A113338 41,59,419,473,1193,1283,2363,2489,3929,4091,5891,6089,8249,8483, %T A113338 11003,11273,14153,14459,17699,18041,21641,22019,25979,26393,30713, %U A113338 31163,35843,36329,41369,41891,47291,47849,53609,54203,60323,60953 %N A113338 Positive integers of the form (18*m^2+1)/11. %C A113338 Here m=(11*(2*n-1)-9*(-1)^n)/4 for n>0. %C A113338 (18*m^2 + 1)/11 is an integer for m=5+11k and m=6+11k, k=0,1,2,.... [ Corrected by _Bruno Berselli_, Jun 28 2010] %H A113338 Bruno Berselli, <a href="/A113338/b113338.txt">Table of n, a(n) for n = 1..10000</a>. %H A113338 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1). %F A113338 From _Bruno Berselli_, Jun 29 2010: (Start) %F A113338 G.f.: x*(41+18*x+278*x^2+18*x^3+41*x^4)/((1+x)^2*(1-x)^3). %F A113338 a(n) = a(-n+1) = a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5). %F A113338 a(n) = (198*n*(n-1)-81*(2*n-1)*(-1)^n+83)/4. (End) %o A113338 (PARI) a(n)=(198*n*(n-1)-81*(2*n-1)*(-1)^n+83)/4 \\ _Charles R Greathouse IV_, Oct 07 2015 %Y A113338 Cf. A179088, A179337, A179338, A179339, A179370. %K A113338 nonn,easy %O A113338 1,1 %A A113338 _Zak Seidov_, Jan 08 2006 %E A113338 Definition corrected, comment and cross-reference added by _Bruno Berselli_, Jul 13 2010