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 A255187 #31 Feb 06 2023 06:16:27
%S A255187 0,1,29,84,166,275,411,574,764,981,1225,1496,1794,2119,2471,2850,3256,
%T A255187 3689,4149,4636,5150,5691,6259,6854,7476,8125,8801,9504,10234,10991,
%U A255187 11775,12586,13424,14289,15181,16100,17046,18019,19019,20046,21100
%N A255187 29-gonal numbers: a(n) = n*(27*n-25)/2.
%C A255187 See comments in A255184.
%D A255187 E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 6 (27th row of the table).
%H A255187 Luciano Ancora, <a href="/A255187/b255187.txt">Table of n, a(n) for n = 0..1000</a>
%H A255187 <a href="/index/Pol#polygonal_numbers">Index to sequences related to polygonal numbers</a>
%H A255187 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A255187 G.f.: x*(-1 - 26*x)/(-1 + x)^3.
%F A255187 a(n) = A000217(n) + 26*A000217(n-1).
%F A255187 Product_{n>=2} (1 - 1/a(n)) = 27/29. - _Amiram Eldar_, Jan 22 2021
%F A255187 E.g.f.: exp(x)*(x + 27*x^2/2). - _Nikolaos Pantelidis_, Feb 06 2023
%t A255187 Table[n (27 n - 25)/2, {n, 40}]
%t A255187 PolygonalNumber[29,Range[0,40]] (* _Harvey P. Dale_, Jul 25 2021 *)
%o A255187 (PARI) a(n)=n*(27*n-25)/2 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A255187 Cf. similar sequences listed in A255184.
%K A255187 nonn,easy
%O A255187 0,3
%A A255187 _Luciano Ancora_, Apr 04 2015