Irregular triangle read by rows in which row n lists primitive prime factors of the repunit (10^n - 1)/9 (A002275(n)).

A204845

Irregular triangle read by rows in which row n lists primitive prime factors of the repunit (10^n - 1)/9 (A002275(n)).

Terms

    a(0) =1a(1) =11a(2) =3a(3) =37a(4) =101a(5) =41a(6) =271a(7) =7a(8) =13a(9) =239a(10) =4649a(11) =73a(12) =137a(13) =333667a(14) =9091a(15) =21649a(16) =513239a(17) =9901a(18) =53a(19) =79a(20) =265371653a(21) =909091a(22) =31a(23) =2906161a(24) =17a(25) =5882353a(26) =2071723a(27) =5363222357a(28) =19a(29) =52579

External references