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A262573 Concatenation of the numbers from 1 to n but omitting 3. 0

%I #28 Sep 17 2019 17:25:13

%S 1,12,124,1245,12456,124567,1245678,12456789,1245678910,124567891011,

%T 12456789101112,1245678910111213,124567891011121314,

%U 12456789101112131415,1245678910111213141516,124567891011121314151617,12456789101112131415161718,1245678910111213141516171819,124567891011121314151617181920

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

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

%C No other primes through a(10000). - _Robert Price_, Nov 04 2018

%t DeleteDuplicates[Table[FromDigits[Flatten[IntegerDigits[Complement[Range[n], {3}]]]], {n, 20}]] (* _Robert Price_, Nov 05 2018 *)

%t Join[{1,12},Table[FromDigits[Join[{1,2},Flatten[IntegerDigits/@Range[4,n]]]],{n,4,20}]] (* _Harvey P. Dale_, Sep 17 2019 *)

%Y Cf. A007908, A262299, A262571-A262582.

%Y See A262300 for more about this problem.

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_, Sep 25 2015

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)