%I A011820
%S A011820 2,6,32,203,1144,5345,20926,70506,209746,562727,1384758,3167606,
%T A011820 6807620,13863904,26941700,50245591,90358146,157312324,266040452,
%U A011820 438299013,705186944,1110395771,1714352818,2599444040,3876530866
%N A011820 M-sequences m_0,...,m_4 with m_1 < n.
%D A011820 S. Linusson, The number of M-sequences and f-vectors, Combinatorica, 
               19 (1999), 255-266.
%F A011820 a(n)= ( 4*n^10 +61*n^9 +408*n^8 +1722*n^7 +6132*n^6 +18333*n^5 +41072*n^4 
               +88748*n^3 +133824*n^2 +193536*n +241920 )/120960, (frank.ellermann(AT)t-online.de).
%Y A011820 Cf. A011819 ... A011825, A011828.
%Y A011820 Sequence in context: A018940 A055596 A109572 this_sequence A111550 A009686 
               A012318
%Y A011820 Adjacent sequences: A011817 A011818 A011819 this_sequence A011821 A011822 
               A011823
%K A011820 nonn
%O A011820 1,1
%A A011820 Svante Linusson (linusson(AT)math.kth.se)