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 A098698 #9 Nov 08 2017 12:00:05
%S A098698 1,4,64,1778,73848,4188592,306690520,27893327856,3063657097664,
%T A098698 397720778283584,59997757426314624,10373545999796847232,
%U A098698 2032368096229682220160,446879795164524710777856
%N A098698 Main diagonal of array in A098697.
%C A098698 Diagonal of Euler-Seidel matrix with start sequence A000248.
%F A098698 a(n) = Sum_{k=0..n} C(n, k) * A000248(2n-k).
%t A098698 a248[0] = 1; a248[n_] := Sum[Binomial[n, k]*(n - k)^k, {k, 0, n}];
%t A098698 T[0, n_] := T[0, n] = a248[n]; T[k_, n_] := T[k, n] = T[k - 1, n] + T[k - 1, n + 1];
%t A098698 a[n_] := T[n, n];
%t A098698 Table[a[n], {n, 0, 13}] (* _Jean-François Alcover_, Nov 08 2017 *)
%K A098698 nonn
%O A098698 0,2
%A A098698 _Ralf Stephan_, Sep 23 2004