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 A062747 #13 Mar 27 2020 02:56:41
%S A062747 1,7,89,1447,26713,532391,11165785,242851751,5427716185,123901026215,
%T A062747 2876525797465,67710590623655,1612262780199001,38764533106581415,
%U A062747 939825790848884825,22950405085586497447
%N A062747 Row sums of (unsigned) staircase array A062746.
%F A062747 a(n)=N(3; k, x=-1), with the polynomials N(3; k, x) from the staircase array A062746.
%F A062747 a(n) = 2*( Sum_{j = 0..n} (-1)^j*C(3; n-j)*4^(n-j) ) - (-1)^n with C(3; n) := A001764(n) = A062993(n+1, 1) (a Pfaff-Fuss or 3-Raney sequence).
%F A062747 G.f.: (2*c(3; 4*x)-1)/(1+x) with c(3; x)= RootOf(x*_Z^3-_Z +1), the g.f. of A001764 [formula for a(n) and g.f. corrected by _Peter Bala_, Mar 26 2020].
%F A062747 Conjectural recurrence: n*(2*n+1)*a(n) = (4*n-3)*(13*n-4)*a(n-1) + 6*(3*n-1)*(3*n-2)*a(n-2) with a(0) = 1, a(1) = 7. - _Peter Bala_, Mar 25 2020
%K A062747 nonn,easy
%O A062747 0,2
%A A062747 _Wolfdieter Lang_, Jul 12 2001