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 A256649 #40 Aug 04 2025 11:24:22
%S A256649 0,1,30,114,280,555,966,1540,2304,3285,4510,6006,7800,9919,12390,
%T A256649 15240,18496,22185,26334,30970,36120,41811,48070,54924,62400,70525,
%U A256649 79326,88830,99064,110055,121830,134416,147840,162129,177310,193410,210456,228475,247494
%N A256649 29-gonal pyramidal numbers: a(n) = n*(n+1)*(9*n-8)/2.
%C A256649 See comments in A256645.
%D A256649 E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 93 (27th row of the table).
%H A256649 Luciano Ancora, <a href="/A256649/b256649.txt">Table of n, a(n) for n = 0..1000</a>
%H A256649 Luciano Ancora, <a href="/A256645/a256645_1.pdf">Polygonal and Pyramidal numbers</a>, Section 3.
%H A256649 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A256649 G.f.: x*(1 + 26*x)/(1 - x)^4.
%F A256649 a(n) = A000292(n) + 26*A000292(n-1).
%F A256649 From _Elmo R. Oliveira_, Aug 04 2025: (Start)
%F A256649 E.g.f.: exp(x)*x*(2 + 28*x + 9*x^2)/2.
%F A256649 a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)
%t A256649 Table[n (n + 1)(9 n - 8)/2, {n, 0, 40}]
%t A256649 LinearRecurrence[{4, -6, 4, -1}, {0, 1, 30, 114}, 40] (* _Vincenzo Librandi_, Apr 08 2015 *)
%o A256649 (Magma) [n*(n+1)*(9*n-8)/2: n in [0..50]]; // _Vincenzo Librandi_, Apr 08 2015
%Y A256649 Partial sums of A255187.
%Y A256649 Cf. similar sequences listed in A237616.
%Y A256649 Cf. A000292, A256645.
%K A256649 nonn,easy
%O A256649 0,3
%A A256649 _Luciano Ancora_, Apr 07 2015