

A262555


Numbers n such that the concatenation of the decimal numbers 1 through n, but omitting 2, is a prime.


2




OFFSET

1,1


COMMENTS

The corresponding primes are the primes in A262572. Probabilistic arguments suggest the sequence is infinite.
a(6) > 10000, if it exists.  Robert Price, Nov 04 2018


LINKS

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


EXAMPLE

The first two terms correspond to the primes 13 and 134567891011121314151617181920212223242526272829303132333435363738394041 (see A262298).
a(3) corresponds to a prime ending in 103, with 200 digits, a(4) to a probable prime ending in 1713, with 5744 digits, and a(5) to a probable prime ending in 2769, with 9968 digits. These three terms were found by David Broadhurst on Oct 09 2015.


CROSSREFS

Cf. A262572, A262298, A007908.
Sequence in context: A080347 A229080 A289270 * A106978 A260832 A089131
Adjacent sequences: A262552 A262553 A262554 * A262556 A262557 A262558


KEYWORD

nonn,base,more


AUTHOR

N. J. A. Sloane, Oct 09 2015


STATUS

approved



