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 A016947 #33 Jul 02 2025 18:50:42
%S A016947 27,729,3375,9261,19683,35937,59319,91125,132651,185193,250047,328509,
%T A016947 421875,531441,658503,804357,970299,1157625,1367631,1601613,1860867,
%U A016947 2146689,2460375,2803221,3176523,3581577,4019679,4492125,5000211,5545233,6128487,6751269
%N A016947 a(n) = (6*n + 3)^3.
%H A016947 Vincenzo Librandi, <a href="/A016947/b016947.txt">Table of n, a(n) for n = 0..2000</a>
%H A016947 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A016947 Sum_{n>=0} 1/a(n) = 7*zeta(3)/216. - _Amiram Eldar_, Oct 02 2020
%F A016947 a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - _Wesley Ivan Hurt_, Oct 02 2020
%F A016947 G.f.: 27*(1+x)*(1+22*x+x^2)/(-1+x)^4. - _Wesley Ivan Hurt_, Oct 02 2020
%F A016947 From _Amiram Eldar_, Mar 30 2022: (Start)
%F A016947 a(n) = A016945(n)^3.
%F A016947 a(n) = 3^3*A016755(n).
%F A016947 Sum_{n>=0} (-1)^n/a(n) = Pi^3/864. (End)
%e A016947 a(0) = (6*0 + 3)^3 = 3^3 = 27.
%t A016947 Table[(6*n + 3)^3, {n, 0, 25}] (* _Amiram Eldar_, Oct 02 2020 *)
%t A016947 LinearRecurrence[{4,-6,4,-1},{27,729,3375,9261},40] (* _Harvey P. Dale_, Jul 02 2025 *)
%o A016947 (Magma) [(6*n+3)^3: n in [0..50]]; // _Vincenzo Librandi_, May 05 2011
%Y A016947 Cf. A000578, A002117, A016755, A016911, A016923, A016935, A016945, A016946, A016959, A016971.
%K A016947 nonn,easy
%O A016947 0,1
%A A016947 _N. J. A. Sloane_