%I #8 Jun 28 2018 06:20:30
%S 0,0,1,21,330,4931,76064,1257345,22707559,452800399,10023029299,
%T 246756095614,6752175162108,204875755372586,6868905893537535,
%U 253432530143048034,10246233216680784186,452038162651568624259
%N M-sequences from multicomplexes on 4 variables with all monomials of degree 2 but none of degree larger than n.
%D S. Linusson, The number of M-sequences and f-vectors, Combinatorica, 19 (1999), 255-266.
%F a(n) = Sum_{k=2..n} L(4, n, k) where L(p, n, k) = Sum_{i=k..n} L(p-1, n, i) * L(p, i-1, k-1) with boundary conditions L(p, n, n) = L(p, n, -1) = 1 (p >= 0, n >= -1), L(0, n, k) = 0 (0 <= k < n) [from Linusson].
%K nonn
%O 0,4
%A Svante Linusson (linusson(AT)math.kth.se)
%E Offset corrected by _Sean A. Irvine_, Jun 28 2018