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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181820 a(1) =1; for n>1, if A025487(n) = Product p(i)^e(i), then a(n) = Product p(e(i)). 8

%I

%S 1,2,3,4,5,6,7,10,8,11,9,14,12,13,15,22,20,17,21,18,26,16,25,28,19,33,

%T 30,34,24,35,44,23,39,42,38,40,55,27,52,29,50,51,36,49,66,46,56,65,45,

%U 68,31,70,57,32,60,77,78,58,88,85,63,76,37,110,69,48,84,91,75,102,62,54,98,104,95

%N a(1) =1; for n>1, if A025487(n) = Product p(i)^e(i), then a(n) = Product p(e(i)).

%C A permutation of the natural numbers.

%H Amiram Eldar, <a href="/A181820/b181820.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n)=A181819(A025487(n)).

%F a(n)=A122111(A181815(n)).

%e A025487(8) = 24 = 2^3*3 has the exponents (3,1) in its canonical prime factorization. Accordingly, a(8) = prime(3)*prime(1) (i.e., A000040(3)*A000040(1)), which equals 5*2=10.

%Y A181815 is another mapping from the members of A025487 to the positive integers. Also see A181819, A181821.

%K nonn

%O 1,2

%A _Matthew Vandermast_, Dec 07 2010

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 January 16 09:13 EST 2021. Contains 340204 sequences. (Running on oeis4.)