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 A131405 #5 Aug 10 2018 02:24:45 %S A131405 1,2,7,16,37,82,179,384,813,1702,3531,7272,14889,30342,61603,124700, %T A131405 251825,507582,1021535,2053388,4123481,8274002,16591767,33254356, %U A131405 66623317,133432082,267164239,534814024,1070413693,2142098602,4286254091,8575836312,17157057669 %N A131405 Row sums of triangle A131404. %H A131405 Andrew Howroyd, <a href="/A131405/b131405.txt">Table of n, a(n) for n = 0..500</a> %H A131405 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5, -8, 3, 3, -2) %F A131405 From _Andrew Howroyd_, Aug 09 2018: (Start) %F A131405 a(n) = 5*a(n-1) - 8*a(n-2) + 3*a(n-3) + 3*a(n-4) - 2*a(n-5). %F A131405 G.f.: (1 - 3*x + 5*x^2 - 6*x^3 + 4*x^4)/((1 - x)^2*(1 - 2*x)*(1 - x - x^2)). %F A131405 (End) %e A131405 a(4) = 37 = sum of row 4 terms of triangle A131404: (1 + 11 + 13 + 11 + 1). %o A131405 (PARI) Vec((1 - 3*x + 5*x^2 - 6*x^3 + 4*x^4)/((1 - x)^2*(1 - 2*x)*(1 - x - x^2)) + O(x^40)) \\ _Andrew Howroyd_, Aug 09 2018 %Y A131405 Row sums of A131404. %Y A131405 Cf. A131403. %K A131405 nonn %O A131405 0,2 %A A131405 _Gary W. Adamson_, Jul 07 2007 %E A131405 Terms a(10) and beyond from _Andrew Howroyd_, Aug 09 2018