A262573 Concatenation of the numbers from 1 to n but omitting 3.

1, 12, 124, 1245, 12456, 124567, 1245678, 12456789, 1245678910, 124567891011, 12456789101112, 1245678910111213, 124567891011121314, 12456789101112131415, 1245678910111213141516, 124567891011121314151617, 12456789101112131415161718, 1245678910111213141516171819, 124567891011121314151617181920

Offset: 1

Author

N. J. A. Sloane, Sep 25 2015

Keywords

• nonn
• base

Comments

The only prime among the first 98 terms is a(6) = 124567. Does the sequence contain any other primes?

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

Crossrefs

Cf. A007908, A262299, A262571-A262582.

See A262300 for more about this problem.

Programs

Mathematica

DeleteDuplicates[Table[FromDigits[Flatten[IntegerDigits[Complement[Range[n], {3}]]]], {n, 20}]] (* Robert Price, Nov 05 2018 *)
Join[{1,12},Table[FromDigits[Join[{1,2},Flatten[IntegerDigits/@Range[4,n]]]],{n,4,20}]] (* Harvey P. Dale, Sep 17 2019 *)