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 A201124 #11 Jul 22 2025 16:06:29 %S A201124 2,2,18,71,83,747,1679,7538,22394,65186,177578,370898,1497119,2428283, %T A201124 5285858,47572722,129918074,274553378,1128916463,2107864523, %U A201124 6892205234,25794120683,14732727599,132594548391,214986322034,1934876898306,8608610563379,24645805942151,63317186094563,94369472696663 %N A201124 Differences between odd powers of 3 and the next smaller square. %H A201124 Hugo Pfoertner, <a href="/A201124/b201124.txt">Table of n, a(n) for n = 1..500</a> %F A201124 a(n) = 3^(2*n-1) - floor(sqrt(3^(2*n-1)))^2 %e A201124 a(1)=3^1-1^2=2, a(2)=3^3-5^2=27-25=2, a(3)=3^5-15^2=243-225=18 %t A201124 #-Floor[Sqrt[#]]^2&/@(3^Range[1,61,2]) (* _Harvey P. Dale_, Nov 01 2022 *) %Y A201124 Cf. A051214 %K A201124 nonn %O A201124 1,1 %A A201124 _Hugo Pfoertner_, Nov 27 2011