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 A099963 #10 Aug 03 2021 19:05:00 %S A099963 1,1,2,5,10,23,64,179,514,1685,5940,20676,79319,334819,1373858, %T A099963 6075215,29763791,140830911,707344776,3937348498,21115879847, %U A099963 118932148555,740523625011,4440207749039,27742486678915,190912973144330 %N A099963 Sequence of the next-to-last entries in the rows of A099961. %p A099963 with(linalg):rev:=proc(a) local n, p; n:=vectdim(a): p:=i->a[n+1-i]: vector(n,p) end: ps:=proc(a) local n, q; n:=vectdim(a): q:=i->sum(a[j],j=1..i): vector(n,q) end: pss:=proc(a) local n, q; n:=vectdim(a): q:=proc(i) if i<=n then sum(a[j],j=1..i) else sum(a[j],j=1..n) fi end: vector(n+1,q) end: R[0]:=vector(1,1): for n from 1 to 30 do if n mod 3 = 0 or n mod 3 = 1 then R[n]:=ps(rev(R[n-1])) else R[n]:=pss(rev(R[n-1])) fi od: seq(R[n][vectdim(R[n])-1],n=2..30); # _Emeric Deutsch_, Nov 16 2004 %Y A099963 Cf. A099961, A099962. %K A099963 nonn,easy %O A099963 0,3 %A A099963 _N. J. A. Sloane_, Nov 13 2004 %E A099963 More terms from _Emeric Deutsch_, Nov 16 2004