A067837 a(1)=2; to form a(n+1), append P, the largest prime < a(n), if any and Q, the smallest prime > a(n), at the beginning and the end of a(n), respectively.

2, 23, 192329, 192323192329192341, 192323192329192339192323192329192341192323192329192399

Offset

1,1

Links

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

Example

To form a(2), note that there is no prime before 2 and that 3 is the prime coming immediately after 2. So a(2) = 23. To form a(3), the prime coming immediately before 23 is 19 and the prime coming immediate after 23 is 29. So a(3) = 192329.

Crossrefs

Sequence in context: A369993 A114256 A110714 * A358384 A334616 A089987

Adjacent sequences: A067834 A067835 A067836 * A067838 A067839 A067840

Keyword

base,nonn

Author

Joseph L. Pe, Feb 11 2002

Status

approved