A262573 - OEIS

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

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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