A325868 Number of subsets of {1..n} containing n such that every ordered pair of distinct elements has a different quotient.

1, 2, 4, 6, 14, 24, 52, 84, 120, 240, 548, 688, 1784, 2600, 4236, 5796, 16200, 17568, 49968, 55648, 101360, 176792, 433736, 430032, 728784, 1360928, 2304840, 2990856, 8682912, 7877376, 25243200, 27946656, 46758912, 81457248, 121546416, 114388320, 442583952

Offset

1,2

Links

Fausto A. C. Cariboni, Table of n, a(n) for n = 1..50

Example

The a(1) = 1 through a(5) = 14 subsets:
  {1}  {2}    {3}      {4}      {5}
       {1,2}  {1,3}    {1,4}    {1,5}
              {2,3}    {2,4}    {2,5}
              {1,2,3}  {3,4}    {3,5}
                       {1,3,4}  {4,5}
                       {2,3,4}  {1,2,5}
                                {1,3,5}
                                {1,4,5}
                                {2,3,5}
                                {2,4,5}
                                {3,4,5}
                                {1,2,3,5}
                                {1,3,4,5}
                                {2,3,4,5}

Mathematica

Table[Length[Select[Subsets[Range[n]], MemberQ[#, n]&&UnsameQ@@Divide@@@Subsets[#, {2}]&]], {n, 10}]

Crossrefs

Cf. A025582, A108917, A143823, A196723, A196724.

Cf. A325853, A325854, A325858, A325860, A325861, A325864, A325869.

Sequence in context: A307676 A084685 A219042 * A251581 A151794 A181528

Adjacent sequences: A325865 A325866 A325867 * A325869 A325870 A325871

Keyword

nonn

Author

Gus Wiseman, Jun 02 2019

Extensions

a(21)-a(37) from Fausto A. C. Cariboni, Oct 16 2020

Status

approved