A355223 The k-th rightmost digit of a(n) is the least of the k rightmost digits of n.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 11, 12, 13, 14, 15, 16, 17, 18, 19, 0, 11, 22, 23, 24, 25, 26, 27, 28, 29, 0, 11, 22, 33, 34, 35, 36, 37, 38, 39, 0, 11, 22, 33, 44, 45, 46, 47, 48, 49, 0, 11, 22, 33, 44, 55, 56, 57, 58, 59, 0, 11, 22, 33, 44, 55, 66, 67, 68

Offset

0,3

Comments

Leading zeros are ignored.

Links

Rémy Sigrist, Table of n, a(n) for n = 0..10000

Formula

a(n) <= n with equality iff n belongs to A009994.

a(a(n)) = a(n).

a(n) = 0 iff n is a multiple of 10.

Example

For n = 1402:
- min({1, 4, 0, 2}) = 0,
- min({4, 0, 2}) = 0,
- min({0, 2}) = 0,
- min({2}) = 2,
- so a(1402) = 2.

Prog

(PARI) a(n, base=10) = { my (d=digits(n, base), m=oo); forstep (k=#d, 1, -1, d[k]=m=min(m, d[k])); fromdigits(d, base) }
(Python)
def a(n):
    s, m = str(n), "9"
    return int("".join((m:=min(m, s[-1-k])) for k in range(len(s)))[::-1])
print([a(n) for n in range(69)]) # Michael S. Branicky, Jun 24 2022
(Python)
from itertools import accumulate
def A355223(n): return int(''.join(accumulate(str(n)[::-1], func=min))[::-1]) # Chai Wah Wu, Jun 25 2022

Crossrefs

See A355221, A355222 and A355224 for similar sequences.

Cf. A008592, A009994 (fixed points), A135481 (binary analog).

Sequence in context: A059707 A256754 A265525 * A348179 A349422 A056967

Adjacent sequences: A355220 A355221 A355222 * A355224 A355225 A355226

Keyword

nonn,base,easy

Author

Rémy Sigrist, Jun 24 2022

Status

approved