A241569 Primes of the form: (concatenation of first n positive integers) + 1.

2, 13, 123457, 123456789101112131415161718192021222324252627282931

Offset

1,1

Comments

a(5) = 123...868788+1 (a 167-digit number). - Jon E. Schoenfield, Apr 26 2014

Links

Jinyuan Wang, Table of n, a(n) for n = 1..5

Example

123457 is in sequence because 123456+1 = 123457 is prime.

Mathematica

Select[Table[FromDigits[Flatten[IntegerDigits[Range[n]]]] + 1, {n, 1, 1000}], PrimeQ] (* Bruno Berselli, Apr 27 2014 *)

Prog

(Magma) c:=0; for d in [1..3] do m:=10^d; for n in [m div 10..m-1] do c:=c*m+n; t:=c+1; if IsPrime(t) then t; end if; end for; end for; // Jon E. Schoenfield, Apr 26 2014
(Magma) [t+1: n in [1..1000] | IsPrime(t+1) where t is Seqint(Reverse(&cat[Reverse(Intseq(k)): k in [1..n]]))]; // Bruno Berselli, Apr 27 2014

Crossrefs

Cf. A241570.

Sequence in context: A280798 A118912 A027680 * A262299 A135970 A027738

Adjacent sequences: A241566 A241567 A241568 * A241570 A241571 A241572

Keyword

nonn,base

Author

Vincenzo Librandi, Apr 26 2014

Status

approved