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 A131438 #9 Jun 13 2015 00:52:23 %S A131438 1,8,29,82,207,492,1129,2534,5603,12256,26589,57306,122839,262100, %T A131438 557009,1179598,2490315,5242824,11009989,23068610,48234431,100663228, %U A131438 209715129,436207542,905969587 %N A131438 (2+n)*2^n-2-3*n. %C A131438 Row sums of triangle A131437. %H A131438 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (6,-13,12,-4). %F A131438 Binomial transform of A131439. %F A131438 G.f.: -x*(-1-2*x+6*x^2) / ( (2*x-1)^2*(x-1)^2 ). - R. J. Mathar, Sep 24 2011 %e A131438 a(3) = 19 = sum of row 3 terms of triangle A131437: (7 + 9 + 13). %Y A131438 Cf. A131436, A131437, A131439. %K A131438 nonn,easy %O A131438 1,2 %A A131438 _Gary W. Adamson_, Jul 11 2007 %E A131438 Definition replaced by formula. - R. J. Mathar, Sep 24 2011