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 A093500 #48 Oct 22 2024 14:45:37
%S A093500 11,36,76,131,201,286,386,501,631,776,936,1111,1301,1506,1726,1961,
%T A093500 2211,2476,2756,3051,3361,3686,4026,4381,4751,5136,5536,5951,6381,
%U A093500 6826,7286,7761,8251,8756,9276,9811,10361,10926,11506,12101,12711,13336,13976,14631,15301
%N A093500 a(n) = (15*n^2 + 5*n + 2)/2.
%C A093500 Icosahedral gnomic numbers: first differences of icosahedral numbers.
%C A093500 The sequence is related to other gnomons of polyhedra, known by other more familiar names: triangular (tetrahedral gnomic), hex (cubic gnomic), square pyramidal numbers (octahedral gnomic).
%H A093500 Vincenzo Librandi, <a href="/A093500/b093500.txt">Table of n, a(n) for n = 1..10000</a>
%H A093500 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A093500 From _Colin Barker_, Apr 30 2012: (Start)
%F A093500 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
%F A093500 G.f.: (6*x^2 + 8*x + 1)/(1-x)^3. (End)
%F A093500 E.g.f.: exp(x)*(1 + 10*x + 15*x^2/2). - _Elmo R. Oliveira_, Oct 21 2024
%t A093500 Table[(15n^2+5n+2)/2,{n,50}] (* _Harvey P. Dale_, Jun 28 2014 *)
%o A093500 (Magma) [(15*n^2+5*n+2)/2: n in [1..50]]; // _Vincenzo Librandi_, Aug 16 2011
%o A093500 (PARI) a(n)=(15*n^2+5*n+2)/2 \\ _Charles R Greathouse IV_, Jun 16 2017
%Y A093500 Cf. A000217, A000330, A003215, A005901, A006564.
%K A093500 easy,nonn
%O A093500 1,1
%A A093500 _Michael Joseph Halm_, May 13 2004
%E A093500 New definition from _Ralf Stephan_, Dec 01 2004
%E A093500 Name corrected by _Arkadiusz Wesolowski_, Aug 15 2011