A062353 Primes of the form bbbbba... where a and b are digits.

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

Offset: 1

Author

Amarnath Murthy, Jun 23 2001

Keywords

• nonn
• base
• easy

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

Examples

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

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..260

Crossrefs

Cf. A034845, A061022.

Programs

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 *)

PARI

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

Extensions

More terms from Jason Earls, Jun 26 2001

Corrected and extended by Dean Hickerson, Jul 10 2001