A039987 k th digit of a(n) = number of different digits within 2 places of k (not including k).

11, 111, 122, 212, 221, 1111, 1221, 2122, 2212, 11111, 12212, 12221, 13322, 21221, 22122, 22331, 111111, 122122, 122212, 122221, 212212, 212221, 221221, 1111111, 1221221, 1222122, 1222212, 2122122, 2122212, 2122221, 2212212, 2212221

Offset

0,1

Links

Table of n, a(n) for n=0..31.

Example

2122 works, since 2=|{1,2}|, 1=|{2,2,2}|, 2=|{2,1,2}| and 2=|{1,2}|

Crossrefs

Sequence in context: A231872 A308365 A083278 * A039989 A039990 A269002

Adjacent sequences: A039984 A039985 A039986 * A039988 A039989 A039990

Keyword

base,easy,nonn

Author

Erich Friedman

Status

approved