[go: up one dir, main page]

login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Numbers with 13 divisors.
30

%I #42 Feb 04 2024 01:13:04

%S 4096,531441,244140625,13841287201,3138428376721,23298085122481,

%T 582622237229761,2213314919066161,21914624432020321,

%U 353814783205469041,787662783788549761,6582952005840035281,22563490300366186081,39959630797262576401,116191483108948578241

%N Numbers with 13 divisors.

%C 12th powers of primes. The n-th number with p divisors is equal to the n-th prime raised to power p-1, where p is prime. - _Omar E. Pol_, May 06 2008

%H R. J. Mathar, <a href="/A030631/b030631.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000040(n)^(13-1) = A000040(n)^(12). - _Omar E. Pol_, May 06 2008

%F From _Amiram Eldar_, Jan 24 2021: (Start)

%F Product_{n>=1} (1 + 1/a(n)) = zeta(12)/zeta(24) = 218517792968475/(236364091*Pi^12).

%F Product_{n>=1} (1 - 1/a(n)) = 1/zeta(12) = 638512875/(691*Pi^12) = 1/A013670. (End)

%t (Prime@Range@30)^12 (* _Vladimir Joseph Stephan Orlovsky_, Apr 11 2011 *)

%o (Magma) [p^12: p in PrimesUpTo(100)]; // _Vincenzo Librandi_, Mar 27 2014

%o (PARI) is(n)=isprimepower(n)==12 \\ _Charles R Greathouse IV_, Jun 19 2016

%Y Cf. A000040, A013670, A030629.

%Y Subsequence of A008456.

%K nonn,easy

%O 1,1

%A _Jeff Burch_