

A061283


Smallest number with exactly 2n1 divisors.


14



1, 4, 16, 64, 36, 1024, 4096, 144, 65536, 262144, 576, 4194304, 1296, 900, 268435456, 1073741824, 9216, 5184, 68719476736, 36864, 1099511627776, 4398046511104, 3600, 70368744177664, 46656, 589824, 4503599627370496, 82944
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OFFSET

1,2


COMMENTS

The terms are always squares (because the divisors of a nonsquare N come in pairs, d and N/d, and so their number is always even  N. J. A. Sloane, Dec 26 2018).


LINKS

T. D. Noe, Table of n, a(n) for n=1..1000 (using A005179)


FORMULA

a(n) = Min{k  A000005(k)=2n1}.
a(p) = 2^(p1) for prime p.


EXAMPLE

for n=15, a(n)=144 with 15 divisors: {1,2,3,4,6,8,9,12...}.


CROSSREFS

Cf. A000005, A000290, A005408, A005179, A003680, A016017, A037992, A055079, A048691.
Sequence in context: A162547 A073533 A330689 * A242354 A001264 A307138
Adjacent sequences: A061280 A061281 A061282 * A061284 A061285 A061286


KEYWORD

nonn


AUTHOR

Labos Elemer, May 22 2001


STATUS

approved



