login
A119317
n-th divisor of A087134(n), the smallest number whose n-th divisor is prime (for n > 1).
3
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
1,2
LINKS
MATHEMATICA
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 *)
PROG
(Maxima) 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 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 15 2006
EXTENSIONS
More terms from Amiram Eldar, Feb 06 2019
STATUS
approved