|
Search: id:A117120
|
|
|
| A117120 |
|
a(1)=1. a(n) is smallest positive integer not occurring earlier in the sequence where a(n) is congruent to -1 (mod a(n-1)). |
|
+0
1
|
|
| 1, 2, 3, 5, 4, 7, 6, 11, 10, 9, 8, 15, 14, 13, 12, 23, 22, 21, 20, 19, 18, 17, 16, 31, 30, 29, 28, 27, 26, 25, 24, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 95, 94, 93, 92, 91, 90, 89, 88, 87
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Sequence is a permutation of the positive integers.
The permutation is self-inverse. Except for fixed points 1, 2, 3 it consists completely of 2-cycles: (4,5), (6,7), (8,11), (9,10), (12,15), (13,14), (16,23), (17,22), ..., (24,31), ..., (32,47), ... . - Klaus Brockhaus (klaus-brockhaus(AT)t-online.de)
|
|
FORMULA
|
For n >= 2: If a(n-1) = 2^m, m=positive integer, then a(n)= 2^(m+1)-1. If a(n-1) = 3*2^m, m= nonnegative integer, then a(n) = 3*2^(m+1)-1. Otherwise, a(n) = a(n-1) -1.
|
|
CROSSREFS
|
Sequence in context: A123882 A102454 A085790 this_sequence A127515 A099424 A117955
Adjacent sequences: A117117 A117118 A117119 this_sequence A117121 A117122 A117123
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Leroy Quet (qq-quet(AT)mindspring.com), Apr 19 2006
|
|
EXTENSIONS
|
More terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de)
|
|
|
Search completed in 0.002 seconds
|
