|
| |
|
|
A078294
|
|
Smallest multiple of n in which the most significant occurrence of the digit string of n is preceded and followed by the digit string of (n-1) and (n+1) as can be seen in the forward concatenation of the natural numbers.
|
|
0
|
|
|
|
12, 1230, 234, 3452, 4560, 5670, 6783, 7896, 8910, 910110, 101112, 1112136, 1213147, 1314152, 1415160, 1516177, 16171811, 1718190, 18192006, 19202100, 2021229, 2122230, 2223249, 2324256, 25262700, 2627289, 2728292, 28293009
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Table of n, a(n) for n=1..28.
|
|
|
FORMULA
|
The following inequality obviously holds for n > 1: a(n) >= (n-1)*10^(floor(1+log n) + floor(1+log(n+1))) + n*10^(floor(1+log(n+1))) + n + 1 where log is taken base 10, not base e. - Sam Alexander (amnalexander(AT)yahoo.com), Oct 19 2003
|
|
|
EXAMPLE
|
a(1) = 12 = 012, a(9) = 8910, a(13) = 1213147, 13 is sandwiched between 12 and 14.
|
|
|
CROSSREFS
|
Sequence in context: A033564 A054351 A080814 * A009155 A078296 A209176
Adjacent sequences: A078291 A078292 A078293 * A078295 A078296 A078297
|
|
|
KEYWORD
|
base,nonn
|
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 26 2002
|
|
|
EXTENSIONS
|
Corrected and extended by Sam Alexander (amnalexander(AT)yahoo.com), Oct 19 2003
|
|
|
STATUS
|
approved
|
| |
|
|
