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A130903 Bad primes (version 2). Primes not in A028388. 2

%I #7 Aug 24 2015 02:38:21

%S 2,3,7,13,19,23,31,43,47,61,73,79,83,89,103,107,109,113,131,137,139,

%T 151,157,163,167,173,181,193,197,199,211,229,233,239,241,263,271,277,

%U 281,283,293,313,317,337,349,353,359,367,373,379,383,389,397,401,409,421

%N Bad primes (version 2). Primes not in A028388.

%F {p in A000040 and p not in A028388}.

%p isA028388 := proc(p) local a,n,pmin,pplu; if isprime(p) then a := true ; if p < 5 then RETURN(false) ; fi ; pmin := p ; pplu := p ; while pmin > 2 do pmin := prevprime(pmin) ; pplu := nextprime(pplu) ; if p^2 <= pmin*pplu then a := false ; break ; fi ; od: RETURN(a) ; else RETURN(false) ; fi ; end: isA130903 := proc(p) if not isprime(p) then RETURN(false) ; else RETURN(not isA028388(p)) ; fi ; end: for i from 1 to 100 do p := ithprime(i) ; if isA130903(p) then printf("%d,",p) ; fi ; od: # _R. J. Mathar_, Sep 02 2007

%Y Cf. A000040, A028388, A046869, A068828.

%K easy,nonn

%O 1,1

%A _Jonathan Vos Post_, Aug 22 2007

%E Corrected and extended by _R. J. Mathar_, Sep 02 2007

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)