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

1,2

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

Links

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

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 *)

Crossrefs

Cf. A007908, A262299, A262571-A262582.

See A262300 for more about this problem.

Sequence in context: A125424 A163147 A120918 * A039680 A332690 A016134

Adjacent sequences: A262570 A262571 A262572 * A262574 A262575 A262576

Keyword

nonn,base

Author

N. J. A. Sloane, Sep 25 2015

Status

approved