%I #11 Jul 31 2024 09:35:59
%S 9,18,30,36,45,60,63,84,90,100,108,126,135,150,165,168,198,210,216,
%T 225,234,270,273,280,315,330,360,396,408,420,441,450,459,468,513,540,
%U 546,550,570,588,630,660,675,693,720,756,759,780,784,816,825,828,900,910
%N Products of two triangular numbers each > 1.
%p isA140089 := proc(n)
%p for d in numtheory[divisors](n) minus {1} do
%p if d^2 > n then
%p return false;
%p end if;
%p if isA000217(d) then
%p if isA000217(n/d) then
%p return true;
%p end if;
%p end if;
%p end do:
%p return false;
%p end proc:
%p for n from 1 to 1000 do
%p if isA140089(n) then
%p printf("%d,",n) ;
%p end if;
%p end do: # _R. J. Mathar_, Jul 31 2024
%Y Cf. A000217. Subsequence of A085780.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Jun 27 2008
%E More terms from _Rick L. Shepherd_ and _John W. Layman_, Jul 03 2008