login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056798 Prime powers with even exponents >=0. 10
1, 4, 9, 16, 25, 49, 64, 81, 121, 169, 256, 289, 361, 529, 625, 729, 841, 961, 1024, 1369, 1681, 1849, 2209, 2401, 2809, 3481, 3721, 4096, 4489, 5041, 5329, 6241, 6561, 6889, 7921, 9409, 10201, 10609, 11449, 11881, 12769, 14641, 15625, 16129, 16384 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n for which the geometric mean of divisors of n is an integer. - Ctibor O. Zizka, Sep 29 2008

This is just a special case. In fact, the numbers n for which the geometric mean of divisors of n is an integer are all the squares of integers (A000290). - Daniel Lignon, Nov 29 2014

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A025473(n)^(2*A025474(n)) = A000961(n)^2;

A001222(a(n)) mod 2 = 0;

A003415(a(n)) = A192083(n); A068346(a(n)) = A192084(n). - Reinhard Zumkeller, Jun 26 2011

MATHEMATICA

Take[Union[Flatten[Table[Prime[n]^k, {n, 31}, {k, 0, 14, 2}]]], 45] (* Alonso del Arte, Jul 05 2011 *)

PROG

(PARI) is(n)=my(e=isprimepower(n)); if(e, e%2==0, n==1) \\ Charles R Greathouse IV, Sep 18 2015

CROSSREFS

Cf. A000961, A025475.

Sequence in context: A069560 A075494 A063735 * A036454 A115648 A082522

Adjacent sequences:  A056795 A056796 A056797 * A056799 A056800 A056801

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 28 2000

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 5 22:55 EDT 2020. Contains 333260 sequences. (Running on oeis4.)