|
| |
|
|
A178649
|
|
a(n) = product of nonsquarefree divisors of n.
|
|
2
|
|
|
|
1, 1, 1, 4, 1, 1, 1, 32, 9, 1, 1, 48, 1, 1, 1, 512, 1, 162, 1, 80, 1, 1, 1, 9216, 25, 1, 243, 112, 1, 1, 1, 16384, 1, 1, 1, 279936, 1, 1, 1, 25600, 1, 1, 1, 176, 405, 1, 1, 7077888, 49, 1250, 1, 208
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,4
|
|
|
LINKS
|
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
|
|
|
FORMULA
|
a(n) = A007955(n) / A078599(n) = A007955(n) / A007955(A007947(n)).
a(1) = 1, a(p) = 1, a(pq) = 1, a(pq...z) = 1, a(p^k) = p^(1/2*k*(k+1)-1), for p, q = primes, k = natural numbers, pq...z = product of k (k > 2) distinct primes p, q, ..., z.
|
|
|
EXAMPLE
|
For n = 16, set of such divisors is {4, 8, 16}; a(16) = 4*8*16 = 512.
|
|
|
MATHEMATICA
|
Table[Times@@Select[Divisors[n], !SquareFreeQ[#]&], {n, 60}] (* Harvey P. Dale, Nov 04 2020 *)
|
|
|
PROG
|
(Haskell)
a178649 n = div (a007955 n) (a078599 n)
-- Reinhard Zumkeller, Feb 06 2012
|
|
|
CROSSREFS
|
Sequence in context: A112622 A183104 A183102 * A335502 A119591 A333782
Adjacent sequences: A178646 A178647 A178648 * A178650 A178651 A178652
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Jaroslav Krizek, Dec 25 2010
|
|
|
STATUS
|
approved
|
| |
|
|
