A262299 Let S(n) denote the sequence formed by concatenating the decimal numbers 1,2,3,..., omitting n; a(n) is the smallest prime in S(n), or -1 if no term in S(n) is prime.

2, 13, 124567, 12356789, 123467891011, 123457, 123456891011

Offset: 1

Author

N. J. A. Sloane and Jerrold B. Tunnell, Sep 25 2015

Keywords

• nonn
• base
• more

Comments

A262300 is now the main entry for this question.

Examples

			a(8) = 1234567910111213...1873 (ending at 1873, a 6384-digit probable prime, and too large to display here) was found by _David Broadhurst_ on Sep 27 2015.
a(9) = 1234567810111213141516171819,
a(11) = 123456789101213,
and a(19) = 12345678910111213141516171820212223242526272829.
Sep 28, 2015: _David Broadhurst_ has also found a(10), a(12), a(14), a(16), a(17), a(18), and a(20). See A262300 for their values.
a(13) is at present unknown.
		

Crossrefs

A262300 gives the last term in S(n) when a prime appears for the first time.

See A262571-A262582 for the sequences S(1) through S(12).

Cf. A007908 (which plays the role of S(0)).

For the primes in S(1) and S(2) see A089987, A262298.