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A053212 Number of divisors of the minimal numbers (A007416). 5
1, 2, 3, 4, 6, 5, 8, 9, 10, 12, 7, 16, 15, 18, 14, 20, 24, 21, 30, 32, 27, 28, 11, 36, 25, 40, 48, 42, 22, 45, 13, 60, 35, 54, 50, 56, 64, 33, 72, 26, 63, 80, 44, 84, 90, 70, 96, 75, 39, 81, 100, 66, 49, 108, 120, 112, 52, 17, 55, 128, 126, 88, 144, 105, 160 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A permutation of the natural numbers.

LINKS

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

Index entries for sequences that are permutations of the natural numbers

FORMULA

a(n) = A000005(A007416(n)). - Omar E. Pol, Dec 26 2008

MATHEMATICA

Reap[For[n = 1, n <= 10^5, n++, tau = DivisorSigma[0, n]; If[Abs[Product[DivisorSigma[0, k] - tau, {k, 1, n - 1}]] > 0, Print[tau]; Sow[tau]]]][[2, 1]] (* Jean-François Alcover, Jan 16 2013 *)

PROG

(Haskell)

a053212 = a000005' . a007416  -- Reinhard Zumkeller, Apr 18 2015

CROSSREFS

Cf. A007416, A005179. Inverse permutation to A064787.

Cf. A000005. - Omar E. Pol, Dec 26 2008

Sequence in context: A263265 A263267 A257471 * A095424 A194507 A118316

Adjacent sequences:  A053209 A053210 A053211 * A053213 A053214 A053215

KEYWORD

nonn,nice

AUTHOR

Asher Auel (asher.auel(AT)reed.edu) Dec 16, 1999

EXTENSIONS

More terms from Naohiro Nomoto, Apr 03 2001

STATUS

approved

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Last modified October 17 19:36 EDT 2018. Contains 316293 sequences. (Running on oeis4.)