A081208 Smallest prime which begins with all the n-digit primes.

2357, 11131719232931374143475359616771737983899721

Offset

1,1

Comments

a(4) = 10091013...9967997363 has 4246 digits. - Amiram Eldar, Jul 20 2025

Links

Amiram Eldar, Table of n, a(n) for n = 1..3

Example

a(1) = 2357 because its leading digits are the 1-digit primes, viz. 2, 3, 5 and 7 and it is prime.

Mathematica

a[n_] := Module[{d = Flatten[IntegerDigits[Select[Range[10^(n - 1) + 1, 10^n - 1], PrimeQ]]], m = 1, k}, If[PrimeQ[FromDigits[d]], FromDigits[d], While[!PrimeQ[(k = FromDigits[Join[d, IntegerDigits[m]]])], m += 2]; k]]; Array[a, 3] (* Amiram Eldar, Jul 20 2025 *)

Crossrefs

Sequence in context: A030473 A134649 A135377 * A250990 A269483 A187238

Adjacent sequences: A081205 A081206 A081207 * A081209 A081210 A081211

Keyword

base,nonn,bref

Author

Walter Nissen, Mar 10 2003

Extensions

The next term is too large to include.

Status

approved