A053212 Number of divisors of the minimal numbers (A007416).

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

Offset

1,2

Comments

A permutation of the natural numbers.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from T. D. Noe)

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. A000005, A007416, A005179.

Inverse permutation to A064787.

Sequence in context: A263267 A257471 A369136 * A368108 A351495 A379746

Adjacent sequences: A053209 A053210 A053211 * A053213 A053214 A053215

Keyword

nonn,nice

Author

Asher Auel, Dec 16 1999

Extensions

More terms from Naohiro Nomoto, Apr 03 2001

Status

approved