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 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 Cf. A002808, A141468. Sequence in context: A204918 A322999 A304035 * A268576 A053850 A225498 Adjacent sequences:  A155106 A155107 A155108 * A155110 A155111 A155112 KEYWORD nonn,less AUTHOR Juri-Stepan Gerasimov, Jan 20 2009 EXTENSIONS Edited by N. J. A. Sloane, Jan 30 2009 Corrected (67, 79, 113, 189, 219 removed) by R. J. Mathar, May 10 2010 STATUS approved

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Last modified October 18 10:50 EDT 2019. Contains 328147 sequences. (Running on oeis4.)