A119318 -id:A119318 - cp's OEIS frontend

A119317 n-th divisor of A087134(n), the smallest number whose n-th divisor is prime (for n > 1).

1, 2, 3, 5, 7, 7, 13, 13, 19, 17, 23, 31, 29, 31, 41, 61, 61, 61, 47, 61, 73, 97, 127, 71, 97, 107, 127, 149, 173, 211, 127, 97, 107, 211, 127, 149, 173, 181, 211, 257, 281, 317, 181, 421, 241, 257, 281, 317, 337, 367, 421, 509, 563, 631, 727, 421, 487, 509

Offset: 1

Reinhard Zumkeller, May 15 2006

nonn

Amiram Eldar, Table of n, a(n) for n = 1..10000

Cf. A000040, A119318, A119319.

a[1] = 1; a[n_] := Module[{k = 1, d}, While[DivisorSigma[0, k] < n || ! PrimeQ[d = Divisors[k][[n]]], k++]; d]; Array[a, 30]  (* Amiram Eldar, Feb 06 2019 *)

A119317(n) := block(
   if equal(n,1) then
      return(1),
   for i : 1 do (
      idv : listify(divisors(i)),
      if length(idv) >= n then (
         if primep(idv[n]) then
            return(idv[n])
        )
     )
)$ /* R. J. Mathar, Mar 13 2012 */

More terms from Amiram Eldar, Feb 06 2019

A119319 n-th divisor of A119312(n), the smallest number such that the n-th divisor is squarefree.

Original entry on oeis.org

1, 2, 3, 6, 6, 10, 15, 30, 15, 30, 30, 35, 30, 70, 105, 210, 42, 70, 70, 105, 105, 210, 210, 70, 105, 165, 105, 105, 210, 770, 210, 2310, 210, 330, 105, 210, 330, 210, 385, 455, 462, 770, 770, 1155, 1155, 2310, 2310, 385, 455, 330, 462, 455, 330, 770, 910, 455

Offset: 1

Reinhard Zumkeller, May 15 2006

nonn

Cf. A005117, A119317, A119318.

cp's OEIS Frontend

A119317 n-th divisor of A087134(n), the smallest number whose n-th divisor is prime (for n > 1).

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A119319 n-th divisor of A119312(n), the smallest number such that the n-th divisor is squarefree.

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Author

Keywords

Crossrefs