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 A016948 #17 Mar 30 2022 06:34:19
%S A016948 81,6561,50625,194481,531441,1185921,2313441,4100625,6765201,10556001,
%T A016948 15752961,22667121,31640625,43046721,57289761,74805201,96059601,
%U A016948 121550625,151807041,187388721,228886641,276922881,332150625,395254161,466948881,547981281,639128961
%N A016948 a(n) = (6*n + 3)^4.
%H A016948 Vincenzo Librandi, <a href="/A016948/b016948.txt">Table of n, a(n) for n = 0..2000</a>
%H A016948 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1).
%F A016948 From _Amiram Eldar_, Mar 30 2022: (Start)
%F A016948 a(n) = A016945(n)^4 = A016946(n)^2.
%F A016948 a(n) = 3^4*A016756(n).
%F A016948 Sum_{n>=0} 1/a(n) = Pi^4/7776. (End)
%t A016948 a[n_] := (6*n + 3)^4; Array[a, 50, 0] (* _Amiram Eldar_, Mar 30 2022 *)
%o A016948 (Magma) [(6*n+3)^4: n in [0..50]]; // _Vincenzo Librandi_, May 05 2011
%Y A016948 Cf. A000583, A016756, A016945, A016946, A016947.
%K A016948 nonn,easy
%O A016948 0,1
%A A016948 _N. J. A. Sloane_