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A320389 Product_i prime(i)^e(i), where e are the nonzero exponents in the prime factorization of n, sorted in increasing order. 0
1, 2, 2, 4, 2, 6, 2, 8, 4, 6, 2, 18, 2, 6, 6, 16, 2, 18, 2, 18, 6, 6, 2, 54, 4, 6, 8, 18, 2, 30, 2, 32, 6, 6, 6, 36, 2, 6, 6, 54, 2, 30, 2, 18, 18, 6, 2, 162, 4, 18, 6, 18, 2, 54, 6, 54, 6, 6, 2, 150, 2, 6, 18, 64, 6, 30, 2, 18, 6, 30, 2, 108, 2, 6, 18, 18 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Here the exponents are sorted in increasing order; if they are sorted in decreasing order, we get A046523: the smallest number with the same prime signature as n.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..20000

MAPLE

a:= n-> (l-> mul(ithprime(i)^l[i], i=1..nops(l)))(

             sort(map(i-> i[2], ifactors(n)[2]))):

seq(a(n), n=1..100);  # Alois P. Heinz, Feb 18 2020

PROG

(PARI) a(n)=factorback(matconcat([primes(#n=factor(n)[, 2])~, vecsort(n)]))

CROSSREFS

Cf. A046523.

Sequence in context: A328707 A067824 A107067 * A046801 A316437 A137502

Adjacent sequences:  A320386 A320387 A320388 * A320390 A320391 A320392

KEYWORD

nonn,changed

AUTHOR

M. F. Hasler, Oct 12 2018

STATUS

approved

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Last modified February 22 23:44 EST 2020. Contains 332157 sequences. (Running on oeis4.)