(Translated by https://www.hiragana.jp/)
# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a319003 Showing 1-1 of 1 %I A319003 #10 Jan 16 2023 22:51:28 %S A319003 1,1,3,7,17,38,87,191,420,908,1954,4160,8816,18549,38851,80965,168077, %T A319003 347566,716443,1472344,3017866,6170789,12590805,25640050,52122784, %U A319003 105791068,214413852,434007488,877480395,1772235212,3575967030,7209301989,14523006820 %N A319003 Number of ordered multiset partitions of integer partitions of n where the sequence of LCMs of the blocks is weakly increasing. %C A319003 If we form a multiorder by treating integer partitions (a,...,z) as multiarrows LCM(a,...,z) <= {z,...,a}, then a(n) is the number of triangles of weight n. %H A319003 Andrew Howroyd, Table of n, a(n) for n = 0..50 %e A319003 The a(4) = 17 ordered multiset partitions: %e A319003 {{4}} {{1,3}} {{2,2}} {{1,1,2}} {{1,1,1,1}} %e A319003 {{1},{3}} {{2},{2}} {{1},{1,2}} {{1},{1,1,1}} %e A319003 {{1,1},{2}} {{1,1,1},{1}} %e A319003 {{1},{1},{2}} {{1,1},{1,1}} %e A319003 {{1},{1},{1,1}} %e A319003 {{1},{1,1},{1}} %e A319003 {{1,1},{1},{1}} %e A319003 {{1},{1},{1},{1}} %o A319003 (PARI) seq(n)={my(M=Map()); for(m=1, n, forpart(p=m, my(k=lcm(Vec(p)), z); mapput(M, k, if(mapisdefined(M,k,&z), z, 1 + O(x*x^n)) - x^m))); Vec(1/vecprod(Mat(M)[,2]))} \\ _Andrew Howroyd_, Jan 16 2023 %Y A319003 Cf. A000837, A007716, A063834, A269134, A290103, A316222, A317545, A317546, A319001, A319004. %K A319003 nonn %O A319003 0,3 %A A319003 _Gus Wiseman_, Sep 07 2018 %E A319003 a(0)=1 prepended and terms a(11) and beyond from _Andrew Howroyd_, Jan 16 2023 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE