A173771 Primes of form (4*10^n+23)/9.

3, 7, 47, 4447, 4444444447, 44444444444444444447, 44444444444444444444444447

Offset

1,1

Comments

a(9) has 1310 digits. - Bruno Berselli, Jul 26 2012

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..8

Mathematica

Select[Table[(4*10^n+23)/9, {n, 0, 100}], PrimeQ] (* Vincenzo Librandi, Jul 26 2012 *)

Prog

(Magma) [a: n in [0..100] | IsPrime(a) where a is (4*10^n+23)div 9 ]; // Vincenzo Librandi, Jul 26 2012

Crossrefs

Cf. A173772

Equals 3 followed by A092480 (primes of the form 40*R_n + 7). - Klaus Brockhaus and R. J. Mathar, Feb 27 2010

Cf. A056682.

Sequence in context: A031440 A331038 A001566 * A019039 A077559 A330020

Adjacent sequences: A173768 A173769 A173770 * A173772 A173773 A173774

Keyword

nonn

Author

Vincenzo Librandi, Feb 24 2010

Status

approved