A103965 Numbers n such that the string n10n is the decimal expansion of a prime number.

9, 27, 41, 81, 111, 113, 117, 183, 191, 219, 231, 261, 279, 281, 309, 321, 339, 363, 377, 399, 401, 411, 429, 449, 461, 467, 477, 479, 497, 503, 513, 539, 549, 567, 603, 633, 653, 659, 689, 693, 707, 723, 731, 737, 747, 773, 843, 849, 887, 891, 911, 917

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Example

n=9 is in the sequence because n10n = 9109 is prime.
n=113 is in the sequence because n10n = 11310113 is prime.
n=219 is in the sequence because n10n = 21910219 is prime.

Mathematica

n10pQ[n_]:=Module[{idn=IntegerDigits[n]}, PrimeQ[FromDigits[Join[idn, {1, 0}, idn]]]]
Select[Range[1000], n10pQ]  (* Harvey P. Dale, Feb 22 2011 *)

Prog

(Magma) [ n: n in [0..1000] | IsPrime(Seqint(Intseq(n) cat [0, 1] cat Intseq(n))) ]; // Klaus Brockhaus, Feb 03 2011

Crossrefs

Sequence in context: A116455 A103753 A238333 * A069069 A354815 A031088

Adjacent sequences: A103962 A103963 A103964 * A103966 A103967 A103968

Keyword

base,nonn

Author

Parthasarathy Nambi, Mar 30 2005

Status

approved