A056540 a(1) = 1; to form a(n+1), append a(n)-1, a(n)+1 at the beginning and the end of a(n), respectively. Ignore any leading 0's.

1, 12, 111213, 111212111213111214, 111212111213111213111212111213111214111212111213111215

Offset

1,2

Links

Table of n, a(n) for n=1..5.

Example

To form the third term from the second term 12, append 11, 13 to the beginning and end of 12, respectively, to get 111213.

Crossrefs

Sequence in context: A289569 A051368 A103482 * A331093 A369523 A328992

Adjacent sequences: A056537 A056538 A056539 * A056541 A056542 A056543

Keyword

base,easy,nonn

Author

Joseph L. Pe, Feb 09 2002

Status

approved