OFFSET
0,12
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1350 (rows 0..20)
EXAMPLE
Triangle begins:
1
0
0 1
0 0 1 1
0 0 1 2 2 1 1
0 0 0 1 4 5 5 4 2 1 1
0 0 0 1 3 9 15 20 22 20 14 9 5 2 1 1
MATHEMATICA
brute[m_]:=First[Sort[Table[Sort[Sort /@ (m/.Rule@@@Table[{(Union@@m)[[i]], p[[i]]}, {i, Length[p]}])], {p, Permutations[Range[Length[Union@@m]]]}]]];
Table[Length[Union[brute /@ Select[Subsets[Subsets[Range[n], {2}], {k}], Union@@#==Range[n]&]]], {n, 0, 5}, {k, 0, Binomial[n, 2]}]
PROG
(PARI) \\ G(n) defined in A008406.
row(n)={Vecrev(G(n)-if(n>0, G(n-1)), binomial(n, 2)+1)}
{ for(n=0, 7, print(row(n))) } \\ Andrew Howroyd, Feb 19 2024
KEYWORD
nonn,tabf
AUTHOR
Gus Wiseman, Feb 15 2024
EXTENSIONS
a(42) onwards from Andrew Howroyd, Feb 19 2024
STATUS
approved