Divisors of 10^13 - 1.

Terms

a(0) =1a(1) =3a(2) =9a(3) =53a(4) =79a(5) =159a(6) =237a(7) =477a(8) =711a(9) =4187a(10) =12561a(11) =37683a(12) =265371653a(13) =796114959a(14) =2388344877a(15) =14064697609a(16) =20964360587a(17) =42194092827a(18) =62893081761a(19) =126582278481a(20) =188679245283