A283871 For all n, the set consisting of the terms {a(1), a(2), a(3), ..., a(n)} has an even number of digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

11, 22, 33, 44, 55, 66, 77, 88, 99, 1001, 1010, 1100, 1111, 1122, 1133, 1144, 1155, 1166, 1177, 1188, 1199, 1212, 1221, 1313, 1331, 1414, 1441, 1515, 1551, 1616, 1661, 1717, 1771, 1818, 1881, 1919, 1991, 2002, 2020, 2112, 2121, 2200, 2211, 2222, 2233, 2244, 2255, 2266, 2277, 2288, 2299, 2323, 2332, 2424, 2442, 2525

Offset

1,1

Comments

The sequence is started with a(1) = 11 and always extended with the smallest integer not yet present and not leading to a contradiction.

Numbers that have an even number of each digit 0 to 9. - Robert Israel, Jan 07 2024

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

The set consisting of the first 15 terms is {11, 22, 33, 44, 55, 66, 77, 88, 99, 1001, 1010, 1100, 1111, 1122, 1133}; we count there six 0's, sixteen 1's, four 2's, four 3's, etc. All those quantities of digits are even numbers.

Maple

filter:= proc(n) local L; L:= convert(n, base, 10);
   andmap(t -> numboccur(t, L)::even, L) end proc:
select(filter, [$1..10^4]); # Robert Israel, Jan 07 2024

Crossrefs

Cf. A283870.

Sequence in context: A306689 A241899 A226468 * A240927 A272655 A333440

Adjacent sequences: A283868 A283869 A283870 * A283872 A283873 A283874

Keyword

nonn,base

Author

Eric Angelini and Jean-Marc Falcoz, Mar 17 2017

Status

approved