|
|
A155109
|
|
Odd nonprime numbers k such that composite(k) is even.
|
|
0
|
|
|
1, 9, 25, 27, 39, 45, 51, 57, 65, 69, 75, 85, 87, 91, 93, 95, 99, 105, 111, 115, 117, 119, 125, 133, 135, 141, 143, 145, 147, 153, 155, 159, 161, 175, 177, 187, 201, 207, 209, 213, 215, 217, 221, 231, 235, 237, 243, 247, 253, 255, 259, 261, 273, 275, 279, 287
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
MAPLE
|
isA002808 := proc(n) n >= 4 and not isprime(n) ; end proc:
A002808 := proc(n) option remember ; local a; if n = 1 then 4; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; end do; end if; end proc:
for n from 1 to 400 do if type(n, 'odd') and not isprime(n) then c := A002808(n) ; if type(c, 'even') then printf("%d, ", n) ; end if; end if; end do: # R. J. Mathar, May 10 2010
|
|
MATHEMATICA
|
With[{nn=400}, Select[Flatten[Position[Complement[Range[4, nn], Prime[ Range[PrimePi[nn]]]], _?(EvenQ[#]&)]], OddQ[#]&&!PrimeQ[#]&]] (* Harvey P. Dale, Jun 23 2013 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,less
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Corrected (67, 79, 113, 189, 219 removed) by R. J. Mathar, May 10 2010
|
|
STATUS
|
approved
|
|
|
|