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A070226 Numbers n such that the squarefree kernel of n is equal to the number of divisors of n. 2
1, 2, 9, 12, 18, 80, 448, 625, 720, 1200, 1250, 1620, 2025, 4032, 4050, 5625, 7500, 9408, 11250, 11264, 20412, 35721, 53248, 71442, 101376, 117649, 235298, 280000, 371712, 479232, 768320, 907200, 1058841, 1114112, 1270080, 1411788, 1750000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers n such that A007947(n)/A000005(n) = 1. [From Ctibor O. Zizka, Feb 05 2009]

Conjecture : If A000005(n) divides A007947(n) for some n, then A007947(n)=A000005(n). [From Ctibor O. Zizka, Feb 05 2009]

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..150

MATHEMATICA

Select[Range[2000000], DivisorSigma[0, #]==Times@@Transpose[ FactorInteger[#]][[1]]&] (* Harvey P. Dale, Apr 09 2012 *)

CROSSREFS

Cf. A007947, A000005, A033950.

Sequence in context: A324570 A109297 A048768 * A273669 A129829 A053900

Adjacent sequences:  A070223 A070224 A070225 * A070227 A070228 A070229

KEYWORD

nonn

AUTHOR

Jason Earls, May 07 2002

STATUS

approved

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Last modified August 24 02:32 EDT 2019. Contains 326260 sequences. (Running on oeis4.)