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 A047861 #21 Sep 08 2022 08:44:57 %S A047861 1,6,17,41,93,205,445,957,2045,4349,9213,19453,40957,86013,180221, %T A047861 376829,786429,1638397,3407869,7077885,14680061,30408701,62914557, %U A047861 130023421,268435453,553648125,1140850685,2348810237,4831838205,9932111869,20401094653,41875931133 %N A047861 a(n) = T(4,n), array T given by A047858. %C A047861 n-th difference of a(n), a(n-1), ..., a(0) is (5, 6, 7, ...). %H A047861 Vincenzo Librandi, <a href="/A047861/b047861.txt">Table of n, a(n) for n = 0..3000</a> %H A047861 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (5,-8,4). %F A047861 Main diagonal of the array defined by T(0, j)=j+1 j>=0, T(i, 0)=i+1 i>=0, T(i, j)=T(i-1, j-1)+T(i-1, j)+ 3; a(n)=2^(n-1)*(n+8)-3. - _Benoit Cloitre_, Jun 17 2003 %F A047861 a(0)=1, a(1)=6, a(2)=17, a(n) = 5*a(n-1) -8*a(n-2) +4*a(n-3). - _Vincenzo Librandi_, Sep 28 2011 %F A047861 G.f.: (1+x-5*x^2) / ((1-x)*(1-2*x)^2). - _Colin Barker_, Feb 17 2016 %o A047861 (Magma) [2^(n-1)*(n+8)-3: n in [0..30]]; // _Vincenzo Librandi_, Sep 28 2011 %o A047861 (PARI) Vec((1+x-5*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ _Colin Barker_, Feb 17 2016 %K A047861 nonn,easy %O A047861 0,2 %A A047861 _Clark Kimberling_