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 A098230 #34 Feb 10 2023 10:50:45 %S A098230 0,1,75,222,442,735,1101,1540,2052,2637,3295,4026,4830,5707,6657,7680, %T A098230 8776,9945,11187,12502,13890,15351,16885,18492,20172,21925,23751, %U A098230 25650,27622,29667,31785,33976,36240,38577,40987,43470,46026,48655,51357,54132,56980,59901,62895,65962,69102,72315,75601,78960,82392,85897,89475 %N A098230 75-gonal numbers: a(n) = n*(73*n-71)/2. %H A098230 Daniel Starodubtsev, <a href="/A098230/b098230.txt">Table of n, a(n) for n = 0..10000</a> %H A098230 <a href="/index/Pol#polygonal_numbers">Index to sequences related to polygonal numbers</a> %H A098230 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1). %F A098230 G.f.: -x*(1+72*x) / (x-1)^3. - _R. J. Mathar_, Feb 05 2011 %F A098230 a(n) = n*(73*n - 71)/2. %F A098230 E.g.f.: exp(x)*(x + 73*x^2/2). - _Nikolaos Pantelidis_, Feb 10 2023 %p A098230 A098230 := proc(n) n*(73*n-71)/2 ; end proc: %p A098230 seq(A098230(n),n=0..20) ; # _R. J. Mathar_, Feb 04 2011 %o A098230 (Magma) [ n*(73*n - 71)/2: n in [0..50] ]; // _Vincenzo Librandi_, Feb 04 2011 %o A098230 (PARI) a(n)=n*(73*n-71)/2 \\ _Charles R Greathouse IV_, Oct 16 2015 %Y A098230 Cf. A051867, A051873. %K A098230 nonn,easy %O A098230 0,3 %A A098230 _Parthasarathy Nambi_, Oct 25 2004