A262576 - OEIS

%I #27 Nov 05 2018 17:25:23

%S 1,12,123,1234,12345,123457,1234578,12345789,1234578910,123457891011,

%T 12345789101112,1234578910111213,123457891011121314,

%U 12345789101112131415,1234578910111213141516,123457891011121314151617,12345789101112131415161718,1234578910111213141516171819,123457891011121314151617181920

%N Concatenation of the numbers from 1 to n but omitting 6.

%C The only prime among the first 98 terms is a(6) = 123457. Does the sequence contain any other primes?

%C No additional primes through the first 2000 terms. - _Harvey P. Dale_, Sep 27 2018

%C Differs from A132943 at about the 28th terms.

%C No primes, other than a(6), through a(10000). - _Robert Price_, Nov 03 2018

%t Module[{nn=20,c},c=Drop[Range[nn],{6}];Table[FromDigits[Flatten[ IntegerDigits/@ Take[c,n]]],{n,nn-1}]] (* _Harvey P. Dale_, Sep 27 2018 *)

%Y Cf. A132943.

%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