Number of repeating products of any subset of {1, 2, 3, ..., n}.

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =15a(5) =37a(6) =75a(7) =167a(8) =359a(9) =785a(10) =1571a(11) =3447a(12) =6895a(13) =14367a(14) =29783a(15) =61303a(16) =122607a(17) =250783a(18) =501567a(19) =1018031a(20) =2053407a(21) =4127231a(22) =8254463a(23) =16610879a(24) =33311679a(25) =66737871a(26) =133719583a(27) =267778623a(28) =535557247a(29) =1072160511