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 A321628 #7 Dec 07 2018 16:38:49 %S A321628 1,2,8,44,308,2660,27764,343604,4948196,81477188,1510645556, %T A321628 31133831540,705725536868,17441324917508,466571232425012, %U A321628 13427966856358196,413627214916715492,13576185998718106820,472963964292142718516,17429043637241263344116,677320641352700988657764 %N A321628 Row sums of A321627. %p A321628 b := proc(n) option remember; if n = 0 then 2 else %p A321628 add(doublefactorial(2*k-1)*b(n-k), k=1..n) fi end: %p A321628 a := n -> if n = 0 then return 1 else b(n) end: seq(a(n), n=0..20); %Y A321628 Cf. A321627, A193763. %K A321628 nonn %O A321628 0,2 %A A321628 _Peter Luschny_, Dec 07 2018