A262578 Concatenation of the numbers from 1 to n but omitting 8.

1, 12, 123, 1234, 12345, 123456, 1234567, 12345679, 1234567910, 123456791011, 12345679101112, 1234567910111213, 123456791011121314, 12345679101112131415, 1234567910111213141516, 123456791011121314151617, 12345679101112131415161718, 1234567910111213141516171819, 123456791011121314151617181920

Offset: 1

Author

N. J. A. Sloane, Sep 25 2015

Keywords

• nonn
• base

Comments

The first (probable) prime in this sequence is a(1872) = 1234567910111213...1873 (ending at 1873), a 6384-digit probable prime, too large to display here. It was found by David Broadhurst on Sep 27 2015.

No other primes through a(10000). - Robert Price, Nov 04 2018

a(1872) is prime. - Jason Yuen, Nov 17 2024

Crossrefs

Cf. A007908, A262299, A262300, A262571-A262582.

See A262300 for more about this problem.

Programs

Mathematica

Module[{nn=30, c}, c=Drop[Range[nn], {8}]; Table[FromDigits[Flatten[IntegerDigits/@Take[c, n]]], {n, nn-1}]] (* Vincenzo Librandi, Nov 05 2018 *)