login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A100950 Number of partitions of n into a coprime pair of a prime and a semiprime. 2

%I #4 Mar 30 2012 18:50:48

%S 0,0,0,0,0,0,1,0,1,0,3,0,2,1,1,1,5,0,2,1,2,2,4,0,3,3,5,3,4,0,2,4,4,2,

%T 4,1,5,6,3,3,6,1,4,4,6,5,4,2,4,4,7,6,6,3,3,6,7,6,4,1,3,10,7,5,7,3,6,9,

%U 6,5,5,5,4,7,8,7,7,4,6,9,8,9,4,3,7,8,8,9,8,2,4,10,11,10,6,8,7,12,9,8,6,6,5

%N Number of partitions of n into a coprime pair of a prime and a semiprime.

%C A100951(n)<=a(n)<=A100949(n)<=Min{A000720(n), A072000(n)}.

%C a(n) = A000040(i) + A001358(j) for some i and j, such that A000040(i) is not a factor of A001358(j).

%e A100949(21) = #{7+2*7, 11+2*5, 17+2*2} = 3,

%e a(21) = #{11+2*5, 17+2*2} = 2.

%K nonn

%O 1,11

%A _Reinhard Zumkeller_, Nov 23 2004

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 23 11:35 EDT 2024. Contains 371912 sequences. (Running on oeis4.)