OFFSET
1,3
COMMENTS
Similar to A174094, but the maximum integer in each set must be strictly less than 2n here.
EXAMPLE
a(1) counts {1};
a(2) counts {2,3};
a(3) counts {2,3,5} and {3,4,5};
a(4) counts {2,3,5,7}, {3,4,5,7}, and {4,5,6,7};
a(5) counts {4,5,6,7,9} and {5,6,7,8,9}.
MAPLE
with(combstruct) ;
A192298nodiv := proc(s) sl := sort(convert(s, list)) ; for i from 1 to nops(sl)-1 do for j from i+1 to nops(sl) do if op(j, sl) mod op(i, sl) = 0 then return false; end if; end do: end do:true ; end proc:
A192298 := proc(n) a := 0 ; it := iterstructs(Subset({seq(i, i=1..2*n-1)}, size=n)) : while not finished(it) do s := nextstruct(it) ; if nops(s) = n then if A192298nodiv(s) then a := a+1 ; end if; end if; end do: a ; end proc: # R. J. Mathar, Jul 12 2011
CROSSREFS
KEYWORD
nonn,more
AUTHOR
David Brown, Jun 27 2011
STATUS
approved