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 A025931 #20 Jul 14 2021 07:14:00
%S A025931 1,17,188,1726,14343,112371,848506,6255392,45386165,325753285,
%T A025931 2320698744,16447547298,116147697667,818112983159,5752200695702,
%U A025931 40392496919044,283383067688049,1986859807248393,13923911479636180,97546847987676230,683225284523104511
%N A025931 Expansion of 1/((1-2x)(1-3x)(1-5x)(1-7x)).
%H A025931 Alois P. Heinz, <a href="/A025931/b025931.txt">Table of n, a(n) for n = 0..1000</a>
%H A025931 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (17,-101,247,-210)
%F A025931 a(n) = 12*a(n-1) - 35*a(n-2) + 3^(n+1) - 2^(n+1), n >= 2. - _Vincenzo Librandi_, Mar 19 2011
%F A025931 a(n) = 7^(n+3)/40 - 2^(n+3)/15 + 3^(n+3)/8 - 5^(n+3)/12. - _R. J. Mathar_, Mar 19 2011
%p A025931 b:= proc(n, k) option remember; `if`(n=0, 1,
%p A025931 `if`(k=0, 0, ithprime(k)*b(n-1, k)+b(n, k-1)))
%p A025931 end:
%p A025931 a:= n-> b(n, 4):
%p A025931 seq(a(n), n=0..28); # _Alois P. Heinz_, Jul 14 2021
%t A025931 CoefficientList[Series[1/((1-2x)(1-3x)(1-5x)(1-7x)),{x,0,20}],x] (* or *) LinearRecurrence[{17,-101,247,-210},{1,17,188,1726},20] (* _Harvey P. Dale_, Aug 05 2013 *)
%Y A025931 Column k=4 of A343751.
%K A025931 nonn,easy
%O A025931 0,2
%A A025931 _N. J. A. Sloane_