Number of nonempty subsets of {1..n} whose product is divisible by their sum.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =5a(5) =10a(6) =19a(7) =34a(8) =64a(9) =129a(10) =267a(11) =541a(12) =1104a(13) =2253a(14) =4694a(15) =9804a(16) =18894a(17) =38539a(18) =76063a(19) =155241a(20) =311938a(21) =636120a(22) =1299869a(23) =2653853a(24) =5183363a(25) =10272289a(26) =20958448a(27) =40945577a(28) =81745769a(29) =167048919