A262575 Concatenation of the numbers from 1 to n but omitting 5.

1, 12, 123, 1234, 12346, 123467, 1234678, 12346789, 1234678910, 123467891011, 12346789101112, 1234678910111213, 123467891011121314, 12346789101112131415, 1234678910111213141516, 123467891011121314151617, 12346789101112131415161718, 1234678910111213141516171819, 123467891011121314151617181920

Offset

1,2

Comments

The only primes among the first 98 terms are 123467891011 and 123467891011121314151617. See A262552 for further primes in this sequence.

Links

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

Mathematica

DeleteDuplicates[Table[FromDigits[Flatten[IntegerDigits[Complement[Range[n], {5}]]]], {n, 20}]] (* Robert Price, Nov 05 2018 *)
Join[{1, 12, 123, 1234}, Table[FromDigits[Flatten[IntegerDigits/@Drop[Range[n], {5}]]], {n, 6, 20}]] (* Harvey P. Dale, Jan 28 2024 *)

Crossrefs

Cf. A007908, A262299, A262571-A262582.

See A262300 for more about this problem.

For primes see A262552.

Sequence in context: A132943 A262576 A362119 * A187871 A187869 A362117

Adjacent sequences: A262572 A262573 A262574 * A262576 A262577 A262578

Keyword

nonn,base

Author

N. J. A. Sloane, Sep 25 2015

Status

approved