login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A325880 Number of maximal subsets of {1..n} containing n such that every ordered pair of distinct elements has a different difference. 9
1, 1, 2, 2, 4, 8, 8, 10, 18, 34, 50, 70, 78, 89, 120, 181, 277, 401, 561, 728, 867, 1031, 1219, 1537 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Also the number of maximal subsets of {1..n} containing n such that every orderless pair of (not necessarily distinct) elements has a different sum.

LINKS

Table of n, a(n) for n=1..24.

EXAMPLE

The a(2) = 1 through a(9) = 18 subsets:

  {1,2}  {1,3}  {1,2,4}  {1,2,5}  {1,2,6}  {2,3,7}    {3,5,8}    {4,6,9}

         {2,3}  {1,3,4}  {1,4,5}  {1,3,6}  {2,4,7}    {4,5,8}    {5,6,9}

                         {2,3,5}  {1,4,6}  {2,6,7}    {1,2,4,8}  {1,2,4,9}

                         {2,4,5}  {1,5,6}  {3,4,7}    {1,2,6,8}  {1,2,6,9}

                                  {2,3,6}  {4,5,7}    {1,3,4,8}  {1,2,7,9}

                                  {2,5,6}  {4,6,7}    {1,3,7,8}  {1,3,4,9}

                                  {3,4,6}  {1,2,5,7}  {1,5,6,8}  {1,3,8,9}

                                  {3,5,6}  {1,3,6,7}  {1,5,7,8}  {1,4,8,9}

                                                      {2,3,6,8}  {1,6,7,9}

                                                      {2,4,7,8}  {1,6,8,9}

                                                                 {2,3,5,9}

                                                                 {2,3,7,9}

                                                                 {2,4,5,9}

                                                                 {2,4,8,9}

                                                                 {2,6,7,9}

                                                                 {2,6,8,9}

                                                                 {3,4,7,9}

                                                                 {3,5,8,9}

MATHEMATICA

fasmax[y_]:=Complement[y, Union@@(Most[Subsets[#]]&/@y)];

Table[Length[fasmax[Select[Subsets[Range[n]], MemberQ[#, n]&&UnsameQ@@Subtract@@@Subsets[Union[#], {2}]&]]], {n, 0, 10}]

CROSSREFS

Cf. A002033, A108917, A143823, A143824, A196723.

Cf. A325858, A325859, A325861, A325867, A325869, A325879, A325992.

Sequence in context: A160159 A283241 A101651 * A132007 A094605 A217662

Adjacent sequences:  A325877 A325878 A325879 * A325881 A325882 A325883

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Jun 02 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 26 17:02 EDT 2020. Contains 334630 sequences. (Running on oeis4.)