|
|
A115305
|
|
a(n) = if n<5 then n else 5*a(floor(n/5)) + 4 - n mod 5.
|
|
10
|
|
|
1, 2, 3, 4, 9, 8, 7, 6, 5, 14, 13, 12, 11, 10, 19, 18, 17, 16, 15, 24, 23, 22, 21, 20, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Self-inverse permutation of the natural numbers;
if n is written in base 5 representation, then a(n) is the value after replacing all digits d (but not the leading one) by 4-d.
|
|
LINKS
|
|
|
MATHEMATICA
|
Table[d = IntegerDigits[n, 5]; FromDigits[Prepend[4 - Rest@d, d[[1]]], 5], {n, 72}] (* Ivan Neretin, Apr 26 2017 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|