|
Search: id:A163639
|
|
|
| A163639 |
|
The count of odd numbers from prime(n) up to the n-th odd nonprime, A014076(n). |
|
+0
1
|
|
| 1, 4, 6, 8, 8, 8, 9, 9, 9, 9, 10, 8, 8, 8, 9, 7, 6, 8, 6, 6, 7, 5, 5, 3, 2, 2, 2, 3, 4, 3, 5, 6, 8, 8, 11, 10, 12, 12, 13, 15, 17, 15, 19, 18, 19, 18, 22, 27, 27, 27, 26, 28, 28, 32, 32, 32, 34, 34, 36, 37, 36, 40, 46, 47, 47, 47, 51, 52, 56, 54, 55, 57, 60, 61, 63, 63, 65, 67, 68, 69
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
The count includes these two odd numbers themselves and is conducted in both
directions with a positive result independent of which of the two limits is larger.
|
|
FORMULA
|
a(n) = 1+(M-m)/2, n>1, where M=max(A000040(n),A014076(n)) and m=min(A000040(n),A014076(n)).
|
|
EXAMPLE
|
a(2)=4 counts the 4 numbers 3, 5, 7, and 9. a(3)=6 counts the 6 numbers 5, 7, 9, 11, 13, and 15.
|
|
MAPLE
|
A014076 := proc(n) if n = 1 then 1; else for a from procname(n-1)+2 by 2 do if not isprime(a) then RETURN(a) ; fi; od: fi; end:
A163639 := proc(n) if n = 1 then 1; else onpr := A014076(n) ; pr := ithprime(n) ; 1+(max(onpr, pr)-min(onpr, pr))/2 fi; end:
seq(A163639(n), n=1..100) ; # R. J. Mathar, Aug 06 2009
|
|
CROSSREFS
|
Cf. A000040, A005408, A014076.
Sequence in context: A083257 A141219 A159576 this_sequence A095253 A027709 A079775
Adjacent sequences: A163636 A163637 A163638 this_sequence A163640 A163641 A163642
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Aug 02 2009
|
|
EXTENSIONS
|
Edited and corrected R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 06 2009
|
|
|
Search completed in 0.002 seconds
|
