

A061701


Smallest number m such that GCD of d(m^2) and d(m) is 2n+1.


3



1, 12, 4608, 1728, 1260, 509607936, 2985984, 144, 56358560858112, 5159780352, 302400, 6232805962420322304, 1587600, 900900, 201226394483583074212773888, 15407021574586368, 248832
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OFFSET

0,2


COMMENTS

Comment from Dean Hickerson (dean.hickerson(AT)yahoo.com), Jun 23, 2001: a(n) exists for every n. In other words, every positive odd integer k is equal to the GCD of d(m^2) and d(m) for some m. To see this, let m = 2^(k^2  1) * 3^((k1)/2). Then d(m) = k^2 * (k+1)/2 and d(m^2) = (2 k^2  1) * k. Both of these are divisible by k and (8k4) d(m)  (2k+1) d(m^2) = k, so the GCD is k.


LINKS

Table of n, a(n) for n=0..16.


FORMULA

a(n) = Min[m : GCD[d(m^2), d(m)] = 2n+1]


EXAMPLE

For n = 7, GCD[d(20736),d(144)] = GCD[45,15] = 15 = 2*7+1.


CROSSREFS

Cf. A000005, A000290, A048691.
Sequence in context: A127233 A169657 A009094 * A236067 A134821 A229669
Adjacent sequences: A061698 A061699 A061700 * A061702 A061703 A061704


KEYWORD

nonn


AUTHOR

Labos Elemer, Jun 18 2001


EXTENSIONS

More terms from David Wasserman, Jun 20 2002


STATUS

approved



