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 A155878 a(0)=4; for n > 0, a(n) is the smallest composite number c > a(n-1) such that c + n is also composite. 1
 4, 8, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 26, 27, 28, 30, 32, 33, 34, 35, 36, 39, 40, 42, 44, 45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 62, 63, 64, 65, 66, 69, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 86, 87, 88, 90, 91, 93, 94, 95, 96, 98, 99, 102, 104, 105, 106, 108 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS EXAMPLE a(0)=4. Adding a(0) to n=0 gives 4+0=4, which is a composite number; adding a(1) to n=1 gives 8+1=9 which is composite; adding a(2) to n=2 gives 10+2=12 which is composite; adding a(3) to n=3 gives 12+3=15 which is composite; etc. MAPLE isA002808 := proc(n) option remember; RETURN(n>= 4 and not isprime(n)) ; end: A155878:= proc(n) option remember; local a; if n = 0 then 4; else for a from procname(n-1)+1 do if isA002808(a) and isA002808(a+n) then RETURN(a) ; fi; od: fi; end: seq(A155878(n), n=0..100) ; # R. J. Mathar, Jan 31 2009 CROSSREFS Cf. A155874. Sequence in context: A310974 A310975 A310976 * A029886 A102218 A257586 Adjacent sequences:  A155875 A155876 A155877 * A155879 A155880 A155881 KEYWORD base,easy,nonn AUTHOR Eric Angelini, Jan 29 2009 EXTENSIONS Extended by R. J. Mathar, Jan 31 2009 Name edited by Jon E. Schoenfield, Jan 20 2019 STATUS approved

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Last modified January 24 19:34 EST 2022. Contains 350565 sequences. (Running on oeis4.)