login
Irregular triangle read by rows: row n lists divisors of n^2 in decreasing order.
0

%I #14 Aug 03 2018 17:44:10

%S 1,4,2,1,9,3,1,16,8,4,2,1,25,5,1,36,18,12,9,6,4,3,2,1,49,7,1,64,32,16,

%T 8,4,2,1,81,27,9,3,1,100,50,25,20,10,5,4,2,1,121,11,1,144,72,48,36,24,

%U 18,16,12,9,8,6,4,3,2,1,169,13,1,196,98,49,28,14

%N Irregular triangle read by rows: row n lists divisors of n^2 in decreasing order.

%e Triangle begins:

%e 1;

%e 4, 2, 1;

%e 9, 3, 1;

%e 16, 8, 4, 2, 1;

%e 25, 5, 1;

%e 36, 18, 12, 9, 6, 4, 3, 2, 1;

%e 49, 7, 1;

%e 64, 32, 16, 8, 4, 2, 1;

%e 81, 27, 9, 3, 1;

%e 100, 50, 25, 20, 10, 5, 4, 2, 1;

%e 121, 11, 1;

%e 144, 72, 48, 36, 24, 18, 16, 12, 9, 8, 6, 4, 3, 2, 1;

%e 169, 13, 1;

%e 196, 98, 49, 28, 14, 7, 4, 2, 1;

%e 225, 75, 45, 25, 15, 9, 5, 3, 1;

%e 256, 128, 64, 32, 16, 8, 4, 2, 1;

%e 289, 17, 1;

%e 324, 162, 108, 81, 54, 36, 27, 18, 12, 9, 6, 4, 3, 2, 1;

%e 361, 19, 1;

%e 400, 200, 100, 80, 50, 40, 25, 20, 16, 10, 8, 5, 4, 2, 1;

%Y cf. A056538.

%K nonn,tabf

%O 1,2

%A _Kritsada Moomuang_, May 09 2018