|
|
A306747
|
|
Untouchable numbers with a record gap to the next untouchable number.
|
|
5
|
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
The record gap values are 3, 47, 62, 74.
Guy asks "How large can the gaps between untouchable numbers be?"
|
|
REFERENCES
|
Richard K. Guy, Unsolved Problems in Number Theory, 3rd Edition, Springer, 2004, Section B10, p. 101.
|
|
LINKS
|
|
|
EXAMPLE
|
5 is in the sequence since it is an untouchable number and the next untouchable number after it is 52 = 5 + 47 with a record gap of 47. The next gap which is larger than 47 occurs at 2642 which is followed by 2704 = 2642 + 62.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,hard,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|