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 A108107 Numbers n such that the string 1123n is the decimal expansion of a prime number. 0

%I

%S 9,27,31,37,39,49,61,63,97,127,151,181,189,211,217,219,231,247,267,

%T 279,303,307,319,327,349,351,361,379,391,399,403,427,429,439,477,483,

%U 487,501,511,517,531,541,553,561,567,589,597,601,621,631,637,651,667

%N Numbers n such that the string 1123n is the decimal expansion of a prime number.

%C 11 and 23 are primes.

%e 9 is in the sequence because 11239 is prime.

%e 63 is in the sequence because 112363 is prime.

%e 127 is in the sequence because 1123127 is prime.

%p a:=proc(n) local z: z:=nops(convert(n,base,10)): if isprime(1123*10^z+n)=true then n else fi end: seq(a(n),n=1..750); (Deutsch)

%o (MAGMA) [ n: n in [1..700] | IsPrime(Seqint(Intseq(n) cat [3, 2, 1, 1])) ];

%Y Cf. A107645, A107644.

%K nonn,base

%O 1,1

%A _Parthasarathy Nambi_, Jun 25 2005

%E More terms from _Emeric Deutsch_, Jul 02 2005

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Last modified July 19 12:49 EDT 2019. Contains 325159 sequences. (Running on oeis4.)