A087529 - OEIS

%I #12 Sep 21 2024 12:26:34

%S 43,34434343,44334343,44343433,3334344443,3343443443,3344334443,

%T 3344344343,3344434433,3433434443,3433444433,3434444333,3443343443,

%U 3444334343,4334433443,4334443433,4343444333,4344333443,4344433343,4344443333,4433343443,4433344343,4434334343

%N Primes consisting only of digits 3 and 4 occurring with equal frequency.

%C There are 18 digit pairs which can produce such primes. (1,0),(1,3),(1,4),(1,6),(1,7),(1,9),(2,3),(2,9),(3,4),(3,5),(3,7),(3,8),(4,7),(4,9),(5,9),(6,7),(7,9),(8,9).

%H Harvey P. Dale, <a href="/A087529/b087529.txt">Table of n, a(n) for n = 1..5000</a>

%t Select[FromDigits/@Flatten[Permutations/@Table[PadRight[{},2n,{4,3}],{n,5}],1],PrimeQ]//Sort (* _Harvey P. Dale_, Aug 08 2017 *)

%o (PARI) \\ Needs B() from A087510.

%o concat(vector(6,k,B(k,3,4,isprime))) \\ _Andrew Howroyd_, Sep 21 2024

%Y Cf. A087510, A087511, A087528.

%K base,nonn

%O 1,1

%A _Paul D. Hanna_ and _Amarnath Murthy_, Sep 12 2003