A286706 Primes in A077309.

23, 4567, 78910111213, 25262728293031323334353637383940414243444546474849

Offset

1,1

Comments

That is, primes formed from concatenation of k numbers starting with k.

Subsequence of A052087.

a(5) must be larger than A077309(2500).

A077309(k) is prime for k = {2, 4, 7, 25, ...}. - Michael De Vlieger, May 13 2017

Links

Table of n, a(n) for n=1..4.

Eric Weisstein's World of Mathematics, Consecutive Number Sequences

Example

The prime 4567 is a term since it is the concatenation of 4 decimal numbers beginning with the number 4. - Michael De Vlieger, May 13 2017

Mathematica

Select[Table[FromDigits@ Flatten@ Take[#, {n, n + (n - 1)}], {n, Ceiling[Length[#]/2]}], PrimeQ] &@ Array[IntegerDigits, 10^3] (* Michael De Vlieger, May 13 2017 *)

Crossrefs

Cf. A077309, A052087, A035333, A053067.

Sequence in context: A103443 A059000 A233235 * A366585 A134801 A059932

Adjacent sequences: A286703 A286704 A286705 * A286707 A286708 A286709

Keyword

base,easy,nonn

Author

XU Pingya, May 12 2017

Status

approved