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 A262574 Concatenation of the numbers from 1 to n but omitting 4. 0
 1, 12, 123, 1235, 12356, 123567, 1235678, 12356789, 1235678910, 123567891011, 12356789101112, 1235678910111213, 123567891011121314, 12356789101112131415, 1235678910111213141516, 123567891011121314151617, 12356789101112131415161718, 1235678910111213141516171819, 123567891011121314151617181920 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The only prime among the first 98 terms is a(8) = 12356789. Does the sequence contain any other primes? No other primes through a(10000). - Robert Price, Nov 03 2018 LINKS MATHEMATICA DeleteDuplicates[Table[FromDigits[Flatten[IntegerDigits[Complement[Range[n], {4}]]]], {n, 20}]] (* Robert Price, Nov 05 2018 *) CROSSREFS Cf. A007908, A262299, A262571-A262582. See A262300 for more about this problem. Sequence in context: A262575 A187871 A187869 * A159901 A159900 A134802 Adjacent sequences:  A262571 A262572 A262573 * A262575 A262576 A262577 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Sep 25 2015 STATUS approved

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Last modified May 5 17:26 EDT 2021. Contains 343572 sequences. (Running on oeis4.)