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 A253909 #42 May 15 2023 12:35:03
%S A253909 1,1,4,9,16,25,36,49,64,81,100,121,144,169,196,225,256,289,324,361,
%T A253909 400,441,484,529,576,625,676,729,784,841,900,961,1024,1089,1156,1225,
%U A253909 1296,1369,1444,1521,1600,1681,1764,1849,1936,2025,2116,2209,2304,2401,2500
%N A253909 1 together with the positive squares.
%C A253909 Also, right border of A246595 arranged as an irregular triangle.
%C A253909 a(n) are the Engel expansion of A070910. - _Benedict W. J. Irwin_, Dec 15 2016
%H A253909 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A253909 a(n) = A028310(n)^2.
%F A253909 a(n) = 3*a(n-1)-3*a(n-2)+a(n-3) for n>=4. - _David Neil McGrath_, May 23 2015
%F A253909 G.f.: (x^3-4*x^2+2*x-1)/(x-1)^3. - _David Neil McGrath_, May 25 2015
%F A253909 E.g.f.: 1 + exp(x)*x*(1 + x). - _Stefano Spezia_, Jan 30 2023
%t A253909 Join[{1}, Range[50]^2] (* _Alonso del Arte_, Feb 23 2015 *)
%t A253909 Range[0, 50]^2 /. 0 -> 1 (* _Robert G. Wilson v_, Dec 15 2016 *)
%o A253909 (PARI) a(n)=max(n,1)^2 \\ _Charles R Greathouse IV_, Dec 16 2016
%Y A253909 Cf. A028310, A070910, A246595. Essentially the same as A000290 and A174902.
%K A253909 nonn,easy,mult
%O A253909 0,3
%A A253909 _Omar E. Pol_, Feb 12 2015
%E A253909 Keyword:mult added by _Andrew Howroyd_, Aug 06 2018