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 A017630 #21 Sep 01 2025 17:10:31
%S A017630 81,441,1089,2025,3249,4761,6561,8649,11025,13689,16641,19881,23409,
%T A017630 27225,31329,35721,40401,45369,50625,56169,62001,68121,74529,81225,
%U A017630 88209,95481,103041,110889,119025,127449,136161,145161,154449,164025,173889,184041,194481
%N A017630 a(n) = (12*n+9)^2.
%H A017630 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A017630 From _Harvey P. Dale_, Mar 31 2012: (Start)
%F A017630 a(0)=81, a(1)=441, a(2)=1089, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3).
%F A017630 G.f.: -9*(x^2+22*x+9)/(x-1)^3. (End)
%F A017630 a(n) = 9*A016838(n). - _R. J. Mathar_, Mar 21 2016
%t A017630 (12*Range[0,40]+9)^2 (* or *) LinearRecurrence[{3,-3,1},{81,441,1089},40] (* _Harvey P. Dale_, Mar 31 2012 *)
%o A017630 (PARI) a(n)=(12*n+9)^2 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A017630 Cf. A016838.
%Y A017630 Subsequence of A000290.
%K A017630 nonn,easy,changed
%O A017630 0,1
%A A017630 _N. J. A. Sloane_
%E A017630 More terms from _Jason Yuen_, Sep 01 2025