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 A254474 #35 Feb 06 2023 06:06:33
%S A254474 0,1,30,87,172,285,426,595,792,1017,1270,1551,1860,2197,2562,2955,
%T A254474 3376,3825,4302,4807,5340,5901,6490,7107,7752,8425,9126,9855,10612,
%U A254474 11397,12210,13051,13920,14817,15742,16695,17676,18685,19722,20787,21880
%N A254474 30-gonal numbers: a(n) = n*(14*n-13).
%C A254474 See comments in A255184.
%C A254474 Also star 15-gonal numbers.
%D A254474 E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 6 (28th row of the table).
%H A254474 Luciano Ancora, <a href="/A254474/b254474.txt">Table of n, a(n) for n = 0..1000</a>
%H A254474 Luciano Ancora, <a href="/A256645/a256645_1.pdf">Polygonal and Pyramidal numbers</a>, Section 1.
%H A254474 <a href="/index/Pol#polygonal_numbers">Index to sequences related to polygonal numbers</a>
%H A254474 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A254474 G.f.: x*(-1 - 27*x)/(-1 + x)^3.
%F A254474 a(n) = A000217(n) + 27*A000217(n-1).
%F A254474 a(n) = A051867(n) + 15*A000217(n-1).
%F A254474 Product_{n>=2} (1 - 1/a(n)) = 14/15. - _Amiram Eldar_, Jan 22 2021
%F A254474 E.g.f.: exp(x)*(x + 14*x^2). - _Nikolaos Pantelidis_, Feb 05 2023
%t A254474 Table[n (14 n - 13), {n, 40}]
%o A254474 (PARI) a(n)=n*(14*n-13) \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A254474 Cf. similar sequences listed in A255184.
%K A254474 nonn,easy
%O A254474 0,3
%A A254474 _Luciano Ancora_, Apr 04 2015