# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a330935 Showing 1-1 of 1 %I A330935 #6 Jan 05 2020 08:11:12 %S A330935 1,1,0,1,1,0,1,1,0,1,1,0,1,0,1,1,0,1,2,1,0,1,0,1,0,1,3,2,1,0,1,2,1,0, %T A330935 1,2,0,1,0,1,1,0,1,5,5,0,1,0,1,0,1,1,0,1,2,1,0,1,3,1,0,1,5,8,4,0,1,0, %U A330935 1,0,1,0,1,7,7,1,0,1,0,1,0,1,5,5,1,0,1 %N A330935 Irregular triangle read by rows where T(n,k) is the number of length-k chains from minimum to maximum in the poset of factorizations of n into factors > 1, ordered by refinement. %C A330935 This poset is equivalent to the poset of multiset partitions of the prime indices of n, ordered by refinement. %F A330935 T(2^n,k) = A330785(n,k). %F A330935 T(n,1) + T(n,2) = 1. %e A330935 Triangle begins: %e A330935 1: 16: 0 1 3 2 31: 1 46: 0 1 %e A330935 2: 1 17: 1 32: 0 1 5 8 4 47: 1 %e A330935 3: 1 18: 0 1 2 33: 0 1 48: 0 1 10 23 15 %e A330935 4: 0 1 19: 1 34: 0 1 49: 0 1 %e A330935 5: 1 20: 0 1 2 35: 0 1 50: 0 1 2 %e A330935 6: 0 1 21: 0 1 36: 0 1 7 7 51: 0 1 %e A330935 7: 1 22: 0 1 37: 1 52: 0 1 2 %e A330935 8: 0 1 1 23: 1 38: 0 1 53: 1 %e A330935 9: 0 1 24: 0 1 5 5 39: 0 1 54: 0 1 5 5 %e A330935 10: 0 1 25: 0 1 40: 0 1 5 5 55: 0 1 %e A330935 11: 1 26: 0 1 41: 1 56: 0 1 5 5 %e A330935 12: 0 1 2 27: 0 1 1 42: 0 1 3 57: 0 1 %e A330935 13: 1 28: 0 1 2 43: 1 58: 0 1 %e A330935 14: 0 1 29: 1 44: 0 1 2 59: 1 %e A330935 15: 0 1 30: 0 1 3 45: 0 1 2 60: 0 1 9 11 %e A330935 Row n = 48 counts the following chains (minimum and maximum not shown): %e A330935 () (6*8) (2*3*8)->(6*8) (2*2*2*6)->(2*4*6)->(6*8) %e A330935 (2*24) (2*4*6)->(6*8) (2*2*3*4)->(2*3*8)->(6*8) %e A330935 (3*16) (2*3*8)->(2*24) (2*2*3*4)->(2*4*6)->(6*8) %e A330935 (4*12) (2*3*8)->(3*16) (2*2*2*6)->(2*4*6)->(2*24) %e A330935 (2*3*8) (2*4*6)->(2*24) (2*2*2*6)->(2*4*6)->(4*12) %e A330935 (2*4*6) (2*4*6)->(4*12) (2*2*3*4)->(2*3*8)->(2*24) %e A330935 (3*4*4) (3*4*4)->(3*16) (2*2*3*4)->(2*3*8)->(3*16) %e A330935 (2*2*12) (3*4*4)->(4*12) (2*2*3*4)->(2*4*6)->(2*24) %e A330935 (2*2*2*6) (2*2*12)->(2*24) (2*2*3*4)->(2*4*6)->(4*12) %e A330935 (2*2*3*4) (2*2*12)->(4*12) (2*2*3*4)->(3*4*4)->(3*16) %e A330935 (2*2*2*6)->(6*8) (2*2*3*4)->(3*4*4)->(4*12) %e A330935 (2*2*3*4)->(6*8) (2*2*2*6)->(2*2*12)->(2*24) %e A330935 (2*2*2*6)->(2*24) (2*2*2*6)->(2*2*12)->(4*12) %e A330935 (2*2*2*6)->(4*12) (2*2*3*4)->(2*2*12)->(2*24) %e A330935 (2*2*3*4)->(2*24) (2*2*3*4)->(2*2*12)->(4*12) %e A330935 (2*2*3*4)->(3*16) %e A330935 (2*2*3*4)->(4*12) %e A330935 (2*2*2*6)->(2*4*6) %e A330935 (2*2*3*4)->(2*3*8) %e A330935 (2*2*3*4)->(2*4*6) %e A330935 (2*2*3*4)->(3*4*4) %e A330935 (2*2*2*6)->(2*2*12) %e A330935 (2*2*3*4)->(2*2*12) %t A330935 facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]]; %t A330935 upfacs[q_]:=Union[Sort/@Join@@@Tuples[facs/@q]]; %t A330935 paths[eds_,start_,end_]:=If[start==end,Prepend[#,{}],#]&[Join@@Table[Prepend[#,e]&/@paths[eds,Last[e],end],{e,Select[eds,First[#]==start&]}]]; %t A330935 Table[Length[Select[paths[Join@@Table[{y,#}&/@DeleteCases[upfacs[y],y],{y,facs[n]}],{n},First[facs[n]]],Length[#]==k-1&]],{n,100},{k,PrimeOmega[n]}] %Y A330935 Row lengths are A001222. %Y A330935 Row sums are A317176. %Y A330935 Column k = 1 is A010051. %Y A330935 Column k = 2 is A066247. %Y A330935 Column k = 3 is A330936. %Y A330935 Final terms of each row are A317145. %Y A330935 The version for set partitions is A008826, with row sums A005121. %Y A330935 The version for integer partitions is A330785, with row sums A213427. %Y A330935 Cf. A001055, A002846, A003238, A007716, A281118, A292504, A292505, A318812, A330665, A330727. %K A330935 nonn,tabf %O A330935 1,19 %A A330935 _Gus Wiseman_, Jan 04 2020 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE