

A062353


Primes of the form bbbbba... where a and b are digits.


3



2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 113, 223, 227, 229, 331, 337, 443, 449, 557, 661, 773, 881, 883, 887, 991, 997, 1117, 2221, 3331, 4441, 4447, 5557, 6661, 8887, 11113, 11117, 11119, 22229
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OFFSET

1,1


COMMENTS

Number of terms of n digits: 4, 21, 16, 8, 9, 8, 2, 8, 7, 3, 4, 5, 2, 2, 4, 0, 3, 4, 2, 3, 2, 2, 4, 1, 0, ..., .  Robert G. Wilson v, May 29 2011


LINKS



EXAMPLE

4441 is a member where a=1 and b = 4.


MATHEMATICA

f[n_] := Select[ Union@ Flatten@ Table[ FromDigits@ Join[ Table[b, {n  1}], {a}], {b, 9}, {a, {1, 3, 7, 9}}], PrimeQ]; f[1] = {2, 3, 5, 7}; Array[f, 5] // Flatten (* Robert G. Wilson v, May 29 2011 *)


PROG

(PARI) print1("2, 3, 5, 7"); for(n=2, 20, forstep(k=10^n\91, 10^n9, 10^n\91, for(m=k+1, k+9, if(isprime(m), print1(", "m))))) \\ Charles R Greathouse IV, May 29 2011


CROSSREFS



KEYWORD

nonn,base,easy


AUTHOR



EXTENSIONS



STATUS

approved



