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%I #11 Jan 23 2020 12:33:06
%S 1,11,60,328,1800,9924,54964,305680,1706256,9554620,53653996,
%T 302038488,1703995800,9631951476,54539233380,309296779296,
%U 1756495236128,9987721546860,56857004161180,324008331785320,1848182861702184
%N a(n) = T(2n+2,n), array T as in A055818.
%H G. C. Greubel, <a href="/A055826/b055826.txt">Table of n, a(n) for n = 0..250</a>
%p T:= proc(i, j) option remember;
%p if i=0 or j=0 then 1
%p else add(add(T(h,m), m=0..j), h=0..i-1)
%p fi; end:
%p seq(T(n+2, n), n=0..30); # _G. C. Greubel_, Jan 22 2020
%t T[i_, j_]:= T[i, j]= If[i==0 || j==0, 1, Sum[T[h, m], {h,0,i-1}, {m,0,j}]]; Table[T[n+2, n], {n,0,25}] (* _G. C. Greubel_, Jan 22 2020 *)
%o (Sage)
%o @CachedFunction
%o def T(i, j):
%o if (i==0 or j==0): return 1
%o else: return sum(sum(T(h,m) for m in (0..j)) for h in (0..i-1))
%o [T(n+2, n) for n in (0..30)] # _G. C. Greubel_, Jan 22 2020
%Y Cf. A055818, A055819, A055820, A055821, A055822, A055823, A055824, A055825, A055827, A055828, A055829.
%K nonn
%O 0,2
%A _Clark Kimberling_, May 28 2000