|
| |
|
|
A167595
|
|
The number of nonisolated primes between n-th nonisolated nonprime and n-th isolated nonprime.
|
|
1
|
|
|
|
1, 2, 1, 3, 5, 5, 7, 9, 9, 11, 13, 15, 17, 19, 21, 23, 23, 25, 27, 29, 31, 33, 35, 37, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 61, 63, 65, 67, 69, 71, 73, 75, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 119
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
Table of n, a(n) for n=1..69.
|
|
|
EXAMPLE
|
a(1)=1 (0<3<4); a(2)=2 (1<3&5<6); a(3)=1 (8<11<12); a(4)=3 (9<11&13&17<18); a(5)=5 (10<11&13&17&19&29<30); a(6)=5 (14<17&19&29&31&41<42); a(7)=7 (15<17&19&29&31&41&43&59<60); a(8)=9 (16<17&19&29&31&41&43&59&61&71<72).
|
|
|
MAPLE
|
Contribution from R. J. Mathar, May 30 2010: (Start)
A164276 := proc(n) option remember; if n = 1 then 0; else for a from procname(n-1)+1 do if isA164276(a) then return a; end if; end do; end if: end proc:
A001097 := proc(n) option remember; if n =1 then 3; else for a from procname(n-1)+2 by 2 do if isA001097(a) then return a; end if; end do: end if; end proc:
A167595 := proc(n) a := 0 ; for k from A164276(n)+1 to A014574(n)-1 do if isA001097(k) then a := a+1 ; end if; end do: a ; end proc:
seq(A167595(n), n=1..120) ; (End)
|
|
|
CROSSREFS
|
Cf. A001097 (the nonisolated primes), A014574 (the isolated nonprimes), A164276 (the nonisolated nonprimes), A167511.
Sequence in context: A063705 A184250 A137655 * A179382 A161169 A058202
Adjacent sequences: A167592 A167593 A167594 * A167596 A167597 A167598
|
|
|
KEYWORD
|
nonn,easy
|
|
|
AUTHOR
|
Juri-Stepan Gerasimov ((AT)stepan(AT)rambler.ru), Nov 06 2009
|
|
|
EXTENSIONS
|
More terms from R. J. Mathar, May 30 2010
|
|
|
STATUS
|
approved
|
| |
|
|
