# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/

Search: id:a316974
Showing 1-1 of 1

%I A316974 #12 Feb 07 2020 19:33:54
%S A316974 1,1,4,14,49,173,652,2494
%N A316974 Number of non-isomorphic strict multiset partitions of {1, 1, 2, 2, 3, 3, ..., n, n}.
%C A316974 Also the number of unlabeled multigraphs with n edges, allowing loops, spanning an initial interval of positive integers with no equivalent vertices (two vertices are equivalent if in every edge the multiplicity of the first is equal to the multiplicity of the second). For example, non-isomorphic representatives of the a(2) = 4 multigraphs are {(1,2),(1,3)}, {(1,1),(1,2)}, {(1,1),(2,2)}, {(1,1),(1,1)}.
%e A316974 Non-isomorphic representatives of the a(3) = 14 strict multiset partitions:
%e A316974   (112233),
%e A316974   (1)(12233), (11)(2233), (12)(1233), (112)(233),
%e A316974   (1)(2)(1233), (1)(12)(233), (1)(23)(123), (2)(11)(233), (11)(22)(33), (12)(13)(23),
%e A316974   (1)(2)(3)(123), (1)(2)(12)(33), (1)(2)(13)(23).
%Y A316974 Cf. A001055, A007716, A007717, A007719, A020554, A020555, A045778, A050535, A053419, A061742, A094574, A162247, A316892, A316972.
%K A316974 nonn,more
%O A316974 0,3
%A A316974 _Gus Wiseman_, Jul 17 2018
%E A316974 a(7) from _Andrew Howroyd_, Feb 07 2020

# Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE