%I #22 Sep 12 2022 11:42:17

%S 1,1,2,1,2,4,1,2,3,6,1,2,3,4,6,1,2,3,4,6,12,1,2,3,4,6,8,12,1,2,3,4,5,

%T 6,10,12,1,2,3,4,5,6,8,10,12,1,2,3,4,5,6,8,9,10,12,1,2,3,4,5,6,7,8,9,

%U 10,12,14,1,2,3,4,5,6,7,8,9,10,12,14,15,18,20,1,2,3,4,5,6,7,8,9,10,12,14,15,18,20,24

%N Triangle read by rows: n-th row gives the indices of the n repunits that divide A340549(n).

%e Triangle begins:

%e 1;

%e 1, 2;

%e 1, 2, 4;

%e 1, 2, 3, 6;

%e 1, 2, 3, 4, 6;

%e 1, 2, 3, 4, 6, 12;

%e 1, 2, 3, 4, 6, 8, 12;

%e 1, 2, 3, 4, 5, 6, 10, 12;

%e 1, 2, 3, 4, 5, 6, 8, 10, 12;

%e 1, 2, 3, 4, 5, 6, 8, 9, 10, 12;

%e 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 18;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 18;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 18;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 18, 20;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 18, 20, 24;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24;

%e 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24, 30;

%e ...

%e The 5th row is {1, 2, 3, 4, 6} since A340549(5) = 11222211 is the least integer that is divisible by five repunits and these are R_1, R_2, R_3, R_4 and R_6.

%Y Cf. A002275, A004023, A083230, A340549.

%K nonn,base,tabl

%O 1,3

%A _Bernard Schott_, Jul 28 2022