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A212638 a(n) = n-th 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

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Last modified July 28 04:25 EDT 2021. Contains 346317 sequences. (Running on oeis4.)