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 A262582 Concatenation of the numbers from 1 to n but omitting 12. 19
 1, 12, 123, 1234, 12345, 123456, 1234567, 12345678, 123456789, 12345678910, 1234567891011, 123456789101113, 12345678910111314, 1234567891011131415, 123456789101113141516, 12345678910111314151617, 1234567891011131415161718, 123456789101113141516171819, 12345678910111314151617181920 (list; graph; refs; listen; history; text; internal format)
 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 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. See A262300 for more about this problem. Sequence in context: A060555 A138957 A007908 * A262581 A262580 A262579 Adjacent sequences:  A262579 A262580 A262581 * A262583 A262584 A262585 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Sep 25 2015 STATUS approved

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Last modified May 5 19:06 EDT 2021. Contains 343573 sequences. (Running on oeis4.)