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

1,2

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

Links

Table of n, a(n) for n=1..19.

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 *)

Crossrefs

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

See A262300 for more about this problem.

Sequence in context: A262580 A262579 A057932 * A262577 A132943 A262576

Adjacent sequences: A262575 A262576 A262577 * A262579 A262580 A262581

Keyword

nonn,base

Author

N. J. A. Sloane, Sep 25 2015

Status

approved