A235775 a(n) = A047842(A047842(n)), say what you see, once repeated.

1011, 21, 1112, 1113, 1114, 1115, 1116, 1117, 1118, 1119, 1031, 1112, 3112, 3113, 3114, 3115, 3116, 3117, 3118, 3119, 102112, 3112, 22, 211213, 211214, 211215, 211216, 211217, 211218, 211219, 102113, 3113, 211213, 1213, 211314, 211315, 211316, 211317, 211318

Offset

0,1

Comments

a(n) does not depend on the order of digits of n, a property inherited from A047842. - M. F. Hasler, Jan 11 2024

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Formula

From M. F. Hasler, Jan 11 2024: (Start)

a(n) = a(A328447(n)) = a(m) for all n and all m having the same digits as n, considering their respective multiplicity.

a(n) = A047842(n) =: m iff m is a fixed point of A047842. (End)

Example

a(10) = A047842(1011) = 1031;
a(11) = A047842(21) = 1112;
a(12) = A047842(1112) = 3112;
a(100) = A047842(2011) = 102112;
a(101) = A047842(1021) = 102112;
a(102) = A047842(101112) = 104112.
For n = 20231231, digits of the date 2023-12-31, a(n) = 10213223 = A047842(n) because this is a fixed point of A047842. Since the order of the digits of n does not matter and there are no leading zeros, this holds also for the numbers resulting from notation dd.mm.yyyy or mm/dd/yyyy. - M. F. Hasler, Jan 11 2024

Prog

(Haskell)
a235775 = a047842 . a047842
(Python)
def A235775(n):
    s = str(n)
    s = ''.join(str(s.count(d))+d for d in sorted(set(s)))
    return int(''.join(str(s.count(d))+d for d in sorted(set(s)))) # Chai Wah Wu, Feb 12 2023
(PARI) A235775(n) = A047842(A047842(n)) \\ M. F. Hasler, Jan 11 2024

Crossrefs

Cf. A047842, A328447.

Sequence in context: A266673 A055473 A317526 * A262865 A213315 A345906

Adjacent sequences: A235772 A235773 A235774 * A235776 A235777 A235778

Keyword

nonn,base

Author

Reinhard Zumkeller, Jan 15 2014

Status

approved