|
|
A136182
|
|
a(n) = Product_{k=1..d(n)-1} lcm(b(k), b(k+1)), where b(k) is the k-th positive divisor of n and d(n) = the number of positive divisors of n.
|
|
4
|
|
|
1, 2, 3, 8, 5, 72, 7, 64, 27, 200, 11, 20736, 13, 392, 675, 1024, 17, 23328, 19, 32000, 1323, 968, 23, 23887872, 125, 1352, 729, 87808, 29, 145800000, 31, 32768, 3267, 2312, 6125, 1451188224, 37, 2888, 4563, 204800000, 41, 74680704, 43, 340736
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
a(n) = the product of the terms in row n of A136181.
|
|
LINKS
|
|
|
EXAMPLE
|
The positive divisors of 20 are 1,2,4,5,10,20; lcm(1,2)=2, lcm(2,4)=4, lcm(4,5)=20, lcm(5,10)=10, and lcm(10,20)=20, so a(20) = 2*4*20*10*20 = 32000.
|
|
MATHEMATICA
|
Table[Times@@(LCM@@@Partition[Divisors[n], 2, 1]), {n, 50}] (* Harvey P. Dale, Dec 13 2011 *)
|
|
PROG
|
(PARI) a(n) = {my(d=divisors(n)); prod(k=1, #d-1, lcm(d[k], d[k+1])); } \\ Michel Marcus, Mar 05 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|