|
|
A355224
|
|
The k-th rightmost digit of a(n) is the greatest of the k rightmost digits of n.
|
|
4
|
|
|
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 22, 33, 44, 55, 66, 77, 88, 99, 20, 21, 22, 33, 44, 55, 66, 77, 88, 99, 30, 31, 32, 33, 44, 55, 66, 77, 88, 99, 40, 41, 42, 43, 44, 55, 66, 77, 88, 99, 50, 51, 52, 53, 54, 55, 66, 77, 88, 99, 60, 61, 62, 63, 64, 65, 66, 77
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
Leading zeros are ignored.
|
|
LINKS
|
|
|
FORMULA
|
a(n) >= n with equality iff n belongs to A009996.
a(a(n)) = a(n).
|
|
EXAMPLE
|
For n = 1402:
- max({1, 4, 0, 2}) = 4,
- max({4, 0, 2}) = 4,
- max({0, 2}) = 2,
- max({2}) = 2,
- so a(1402) = 4422.
|
|
PROG
|
(PARI) a(n, base=10) = { my (d=digits(n, base), m=-oo); forstep (k=#d, 1, -1, d[k]=m=max(m, d[k])); fromdigits(d, base) }
(Python)
def a(n):
s, m = str(n), "0"
return int("".join((m:=max(m, s[-1-k])) for k in range(len(s)))[::-1])
(Python)
from itertools import accumulate
def A355224(n): return int(''.join(accumulate(str(n)[::-1], func=max))[::-1]) # Chai Wah Wu, Jun 25 2022
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|