Triangle read by rows: row n lists the proper divisors of n-th perfect number A000396(n).

Terms

a(0) =1a(1) =2a(2) =3a(3) =1a(4) =2a(5) =4a(6) =7a(7) =14a(8) =1a(9) =2a(10) =4a(11) =8a(12) =16a(13) =31a(14) =62a(15) =124a(16) =248a(17) =1a(18) =2a(19) =4a(20) =8a(21) =16a(22) =32a(23) =64a(24) =127a(25) =254a(26) =508a(27) =1016a(28) =2032a(29) =4064