Number of nonempty subsets of {2..n} whose product is divisible by their sum.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =3a(5) =6a(6) =12a(7) =21a(8) =34a(9) =69a(10) =140a(11) =278a(12) =561a(13) =1144a(14) =2367a(15) =4936a(16) =9503a(17) =19368a(18) =38202a(19) =77911a(20) =156458a(21) =318911a(22) =651462a(23) =1329624a(24) =2596458a(25) =5144833a(26) =10494839a(27) =20500025a(28) =40923643a(29) =83620258