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 A257956 #7 May 30 2015 03:07:54 %S A257956 1,6,24,74,220,626,1754,4860,13390,36762,100728,275666,753898,2060924, %T A257956 5632550,15391650,42056008,114907626,313947186,857741852,2343430222 %N A257956 Row sums of A232642, when seen as a triangle read by rows. %C A257956 a(n) <= A166060(n). %F A257956 Conjectures from _Colin Barker_, May 29 2015: (Start) %F A257956 a(n) = 3*a(n-1)+a(n-2)-4*a(n-3)-2*a(n-4) for n>4. %F A257956 G.f.: x*(5*x^2+3*x+1) / ((x^2+x-1)*(2*x^2+2*x-1)). %F A257956 (End) %o A257956 (Haskell) %o A257956 a257956 = sum . a232642_row %Y A257956 Cf. A232642, A166060. %K A257956 nonn %O A257956 1,2 %A A257956 _Reinhard Zumkeller_, May 14 2015