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 A081911 #16 Sep 08 2022 08:45:09
%S A081911 1,5,26,140,775,4375,25000,143750,828125,4765625,27343750,156250000,
%T A081911 888671875,5029296875,28320312500,158691406250,885009765625,
%U A081911 4913330078125,27160644531250,149536132812500,820159912109375
%N A081911 a(n) = 5^n*(n^2 - n + 50)/50.
%C A081911 Binomial transform of A081910 5th binomial transform of (1,0,1,0,0,0,...). Case k=5 where a(n,k) = k^n*(n^2 - n + 2k^2)/(2k^2) with g.f. (1 - 2kx + (k^2+1)x^2)/(1-kx)^3.
%H A081911 Vincenzo Librandi, <a href="/A081911/b081911.txt">Table of n, a(n) for n = 0..150</a>
%H A081911 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (15,-75,125).
%F A081911 a(n) = 5^n*(n^2 - n + 50)/50.
%F A081911 G.f.: (1 - 10x + 26x^2)/(1-5x)^3.
%F A081911 a(n) = 15*a(n-1) - 75*a(n-2) + 125*a(n-3); a(0)=1, a(1)=5, a(2)=26. - _Harvey P. Dale, Jul 22 2011
%t A081911 Table[5^n(n^2-n+50)/50,{n,0,20}] (* or *) LinearRecurrence[{15,-75,125},{1,5,26},20] (* _Harvey P. Dale_, Jul 22 2011 *)
%o A081911 (Magma) [5^n*(n^2-n+50)/50: n in [0..40]]; // _Vincenzo Librandi_, Apr 27 2011
%o A081911 (PARI) a(n)=5^n*(n^2-n+50)/50 \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A081911 Cf. A081912.
%K A081911 easy,nonn
%O A081911 0,2
%A A081911 _Paul Barry_, Mar 31 2003