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A154767 Primes with even largest digit. 4

%I #17 Sep 21 2014 13:53:30

%S 2,41,43,61,83,163,181,211,241,263,281,283,383,401,421,431,433,443,

%T 461,463,487,563,587,601,613,631,641,643,653,661,683,787,811,821,823,

%U 827,853,857,863,877,881,883,887,1021,1061,1063,1087,1163,1181,1187,1201

%N Primes with even largest digit.

%C Relative density 0 in the primes. It is natural to conjecture that there are infinitely many, but can this be proved? - _Charles R Greathouse IV_, Nov 12 2010

%H Robert G. Wilson v, <a href="/A154767/b154767.txt">Table of n, a(n) for n = 1..2500</a>

%p A054055 := proc(n) max( op(convert(n,base,10))) ; end: isA154767 := proc(n) RETURN( isprime(n) and ( A054055(n) mod 2 ) = 0 ) ; end; for n from 1 to 400 do p := ithprime(n) ; if isA154767(p) then printf("%d,",p) ; fi; od: # _R. J. Mathar_, Jan 18 2009

%t fQ[p_] := EvenQ[ Sort[ IntegerDigits[ p]][[-1]]]; Select[ Prime@ Range@ 200, fQ] (* _Robert G. Wilson v_, May 15 2014 *)

%t Select[Prime[Range[200]],EvenQ[Max[IntegerDigits[#]]]&] (* _Harvey P. Dale_, Sep 21 2014 *)

%K nonn,base

%O 1,1

%A _Juri-Stepan Gerasimov_, Jan 15 2009

%E 837 replaced by 827. _R. J. Mathar_, Jan 18 2009

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Last modified March 28 03:28 EDT 2024. Contains 371235 sequences. (Running on oeis4.)