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 A147651 #19 Nov 29 2024 20:29:25
%S A147651 0,27,72,135,216,315,432,567,720,891,1080,1287,1512,1755,2016,2295,
%T A147651 2592,2907,3240,3591,3960,4347,4752,5175,5616,6075,6552,7047,7560,
%U A147651 8091,8640,9207,9792,10395,11016
%N A147651 First trisection of A028560.
%C A147651 Nonnegative k such that k/9 + 1 is a square. - _Bruno Berselli_, Apr 10 2018
%H A147651 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A147651 a(n) = 9*n*(n+2).
%F A147651 a(n) = a(n-1) + 9*A144396(n) for n > 0.
%F A147651 From _Elmo R. Oliveira_, Nov 29 2024: (Start)
%F A147651 G.f.: 9*x*(3 - x)/(1-x)^3.
%F A147651 E.g.f.: 9*x*(3 + x)*exp(x).
%F A147651 a(n) = 9*A005563(n) = 3*A067725(n) = A028560(3*n).
%F A147651 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n >= 3. (End)
%t A147651 Table[9 n (n + 2), {n, 0, 40}] (* _Harvey P. Dale_, Feb 20 2011 *)
%o A147651 (PARI) a(n)=9*n*(n+2) \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A147651 Cf. A005563, A028560, A067725, A144396, A144454.
%K A147651 nonn,easy
%O A147651 0,2
%A A147651 _Paul Curtz_, Nov 09 2008
%E A147651 More terms from _Vincenzo Librandi_, Nov 26 2010