

A212638


a(n) = nth powerful number that is the first integer of its prime signature, divided by its largest squarefree divisor: A003557(A181800(n)).


3



1, 2, 4, 8, 16, 6, 32, 12, 64, 24, 36, 128, 48, 72, 256, 96, 144, 30, 512, 192, 216, 288, 60, 1024, 384, 432, 576, 120, 2048, 768, 864, 180, 1152, 240, 1296, 4096, 1536, 1728, 360, 2304, 480, 2592, 8192, 3072, 3456, 720, 900, 4608, 960, 5184, 1080, 16384
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

The number of second signatures represented by the divisors of A181800(n) equals the number of prime signatures represented among the divisors of a(n). Cf. A212172, A212644.
A permutation of A025487.


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..1000


FORMULA

a(n) = A003557(A181800(n)).


EXAMPLE

6 (whose prime factorization is 2*3) is the largest squarefree divisor of 144 (whose prime factorization is 2^4*3^2). Since 144 = A181800(10), and 144/6 = 24, a(10) = 24.


CROSSREFS

Cf. A003557, A007947, A085082, A181800, A212172, A212642, A212644.
Other permutations of A025487 include A036035, A059901, A063008, A077569, A085988, A086141, A087443, A108951, A181821, A181822.
Sequence in context: A306601 A237851 A167425 * A016018 A333492 A228845
Adjacent sequences: A212635 A212636 A212637 * A212639 A212640 A212641


KEYWORD

nonn


AUTHOR

Matthew Vandermast, Jun 05 2012


STATUS

approved



