A070226 Numbers n such that the squarefree kernel of n is equal to the number of divisors of n.

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

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