A262582 - OEIS

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A262582

Concatenation of the numbers from 1 to n but omitting 12.

1, 12, 123, 1234, 12345, 123456, 1234567, 12345678, 123456789, 12345678910, 1234567891011, 123456789101113, 12345678910111314, 1234567891011131415, 123456789101113141516, 12345678910111314151617, 1234567891011131415161718, 123456789101113141516171819, 12345678910111314151617181920

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OFFSET

1,2

COMMENTS

The first (probable) prime in this sequence is a(960) = 1234567891011131415...961 (ending in 961), found by David Broadhurst, Sep 28 2015.

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

LINKS

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

MATHEMATICA

Module[{nn=30, c}, c=Drop[Range[nn], {12}]; Table[FromDigits[Flatten[IntegerDigits/@Take[c, n]]], {n, nn - 1}]] (* Vincenzo Librandi, Nov 05 2018 *)

CROSSREFS

Cf. A007908, A262299, A262300, A262571-A262582.