A262574 Concatenation of the numbers from 1 to n but omitting 4.

1, 12, 123, 1235, 12356, 123567, 1235678, 12356789, 1235678910, 123567891011, 12356789101112, 1235678910111213, 123567891011121314, 12356789101112131415, 1235678910111213141516, 123567891011121314151617, 12356789101112131415161718, 1235678910111213141516171819, 123567891011121314151617181920

Offset: 1

Author

N. J. A. Sloane, Sep 25 2015

Keywords

• nonn
• base

Comments

The only prime among the first 98 terms is a(8) = 12356789. Does the sequence contain any other primes?

No other primes through a(10000). - Robert Price, Nov 03 2018

Crossrefs

Cf. A007908, A262299, A262571-A262582.

See A262300 for more about this problem.

Programs

Mathematica

DeleteDuplicates[Table[FromDigits[Flatten[IntegerDigits[Complement[Range[n], {4}]]]], {n, 20}]] (* Robert Price, Nov 05 2018 *)