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 A352181 #18 Apr 22 2024 13:34:35 %S A352181 0,5,495,48510,4753490,465793515,45643010985,4472549283020, %T A352181 438264186724980,42945417749765025,4208212675290247475, %U A352181 412361896760694487530,40407257669872769530470,3959498889750770719498535,387990483937905657741325965,38019107927025003687930446040 %N A352181 a(n) = A200993(n)/2. %C A352181 Halves of triangular numbers which are also thirds of triangular numbers. %H A352181 Editors, L'Intermédiaire des Mathématiciens, <a href="/A072256/a072256.pdf">Query 4500: The equation x(x+1)/2 = y*(y+1)/3</a>, L'Intermédiaire des Mathématiciens, 22 (1915), 255-260 (I). %H A352181 Editors, L'Intermédiaire des Mathématiciens, <a href="/A072256/a072256_1.pdf">Query 4500: The equation x(x+1)/2 = y*(y+1)/3</a>, L'Intermédiaire des Mathématiciens, 22 (1915), 255-260 (II). %H A352181 Editors, L'Intermédiaire des Mathématiciens, <a href="/A072256/a072256_2.pdf">Query 4500: The equation x(x+1)/2 = y*(y+1)/3</a>, L'Intermédiaire des Mathématiciens, 22 (1915), 255-260 (III). %H A352181 Editors, L'Intermédiaire des Mathématiciens, <a href="/A072256/a072256_3.pdf">Query 4500: The equation x(x+1)/2 = y*(y+1)/3</a>, L'Intermédiaire des Mathématiciens, 22 (1915), 255-260 (IV). %H A352181 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (99,-99,1). %F A352181 a(n) = A200994(n)/3. %F A352181 From _Chai Wah Wu_, Apr 22 2024: (Start) %F A352181 a(n) = 99*a(n-1) - 99*a(n-2) + a(n-3) for n > 2. %F A352181 G.f.: -5*x/((x - 1)*(x^2 - 98*x + 1)). (End) %F A352181 a(n) = 5*A278620(n). - _Hugo Pfoertner_, Apr 22 2024 %Y A352181 Cf. A200993, A200994, A278620. %K A352181 nonn,easy %O A352181 0,2 %A A352181 _N. J. A. Sloane_, Mar 08 2022