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A084048 Integers m such that the base-10 digit concatenation 2//m//3//m//5//m...//prime(49)//m//prime(50) is prime. 0

%I #10 Jan 07 2021 13:29:19

%S 96,359,546,1422,1644,1980,2241,3458,3606,4530,4629,5018,5090,5114,

%T 5166,7007,7389,8534,9123,9717,9771,10065,10343,10355,10514,10596,

%U 11307,11361,11531,12401,12759,13707,14810,15185,15290,15614,15728,16038

%N Integers m such that the base-10 digit concatenation 2//m//3//m//5//m...//prime(49)//m//prime(50) is prime.

%C This is in the family of sequences fp(j,m)=prime(1)//m//prime(2)//m//prime(3)//...//m//prime(j), of which A032711 = fp(2,m) is a simplest type.

%e 96 is in the sequence because fp(50,k)=2//k//3//k//5//k//7//k//11//k//13...//k//229 fp(50,96)=296396596...22796229 is prime.

%e fp(50,96) is prime number with 219 digits.

%t Select[Range[16100],PrimeQ[FromDigits[Flatten[IntegerDigits/@ Riffle[ Prime[ Range[ 50]],#]]]]&] (* _Harvey P. Dale_, Jan 07 2021 *)

%Y Cf. A083677, A032711.

%K easy,nonn,base

%O 1,1

%A _Farideh Firoozbakht_, Jun 19 2003

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Last modified March 28 04:05 EDT 2024. Contains 371235 sequences. (Running on oeis4.)