|
Search: id:A158877
|
|
|
| A158877 |
|
Definition of a(n): in base-n arithmetic a(n) is the smallest positive integer that is doubled when its least significant digit is moved to become the most significant digit. |
|
+0
3
|
|
| 1012, 102, 13, 1031345242, 103524563142, 1042, 10467842, 105263157894736842
(list; graph; listen)
|
|
|
OFFSET
|
3,1
|
|
|
COMMENT
|
The problem has no solution in base 2, so sequence begins with the base-3 solution. The idea was suggested by a NY Times article (Sunday Magazine of Mar 29, 2009) -- in which Freeman Dyson is said to have solved the base-10 question almost instantaneously when it was posed to him -- and by the ensuing math-fun discussion.
|
|
EXAMPLE
|
Example: For n = 5, the smallest positive integer whose base-5 representation doubles when the rightmost digit is moved to become the leftmost digit is 8 [base 10] = 13 [base 5]. For 31 [base 5] = 16 [base 10].
|
|
CROSSREFS
|
See A087502 (which is the main entry for this sequence) for these numbers written in base 10. Cf. A023094, A159774.
Sequence in context: A035125 A115769 A094946 this_sequence A159774 A072140 A080467
Adjacent sequences: A158874 A158875 A158876 this_sequence A158878 A158879 A158880
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
Daniel Asimov (asimov(AT)msri.org), Mar 28 2009
|
|
EXTENSIONS
|
a(5) corrected by William A. Hoffman III (whoff(AT)robill.com), Apr 19 2009
|
|
|
Search completed in 0.002 seconds
|
