A280582
a(n) = the product of divisors of product of divisors of n.
Original entry on oeis.org
1, 2, 3, 64, 5, 10077696, 7, 2097152, 729, 1000000000, 11, 2116471057875484488839167999221661362284396544, 13, 20661046784, 38443359375, 36028797018963968, 17, 52655678627806560751363688397557640770141543227981824, 19
Offset: 1
For n = 4; a(n) = product of divisors (1*2*4) = 1*2*4*8 = 64.
-
[&*[d: d in Divisors(&*[d: d in Divisors(n)])]: n in [1..100]]
-
Table[Nest[Times @@ Divisors@ # &, n, 2], {n, 19}] (* Michael De Vlieger, Jan 06 2017 *)
A280348
Irregular triangle read by rows in which row n lists the divisors of the sum of the divisors of n.
Original entry on oeis.org
1, 1, 3, 1, 2, 4, 1, 7, 1, 2, 3, 6, 1, 2, 3, 4, 6, 12, 1, 2, 4, 8, 1, 3, 5, 15, 1, 13, 1, 2, 3, 6, 9, 18, 1, 2, 3, 4, 6, 12, 1, 2, 4, 7, 14, 28, 1, 2, 7, 14, 1, 2, 3, 4, 6, 8, 12, 24, 1, 2, 3, 4, 6, 8, 12, 24, 1, 31, 1, 2, 3, 6, 9, 18, 1, 3, 13, 39, 1, 2, 4, 5, 10, 20, 1, 2, 3, 6, 7, 14, 21, 42, 1, 2, 4, 8, 16, 32, 1, 2, 3, 4, 6, 9, 12, 18, 36
Offset: 1
Triangle begins:
1;
1, 3;
1, 2, 4;
1, 7;
1, 2, 3, 6;
1, 2, 3, 4, 6, 12;
1, 2, 4, 8;
1, 3, 5, 15;
1, 13;
1, 2, 3, 6, 9, 18;
1, 2, 3, 4, 6, 12;
1, 2, 4, 7, 14, 28;
1, 2, 7, 14;
1, 2, 3, 4, 6, 8, 12, 24;
1, 2, 3, 4, 6, 8, 12, 24;
1, 31;
1, 2, 3, 6, 9, 18;
1, 3, 13, 39;
1, 2, 4, 5, 10, 20;
1, 2, 3, 6, 7, 14, 21, 42;
1, 2, 4, 8, 16, 32;
1, 2, 3, 4, 6, 9, 12, 18, 36;
1, 2, 3, 4, 6, 8, 12, 24;
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60;
...
For n = 10 the sum of the divisors of 10 is 1 + 2 + 5 + 10 = 18, so row 10 of the triangle lists the divisors of 18: 1, 2, 3, 6, 9, 18.
Showing 1-2 of 2 results.