A033860 Sort-then-add sequence: a(n+1) = a(n) + sort(a(n)).

1, 2, 4, 8, 16, 32, 55, 110, 121, 233, 466, 932, 1171, 2288, 4576, 9143, 10492, 11741, 22888, 45776, 91453, 104912, 116161, 227327, 449704, 494183, 628672, 855350, 890908, 899807, 978706, 1046495, 1191064, 1302533, 1425868, 2671556, 3927223, 6150602, 6163168

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Examples

			After 9143 the next term is 9143 + 1349 = 10492.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A070196, A004185.

Programs

Haskell

a033860 n = a033860_list !! (n-1)
a033860_list = iterate a070196 1
-- Reinhard Zumkeller, Apr 03 2015

Maple

a:= proc(n) option remember; `if`(n=1, 1, (t->
      t+parse(cat(sort(convert(t, base, 10))[])))(a(n-1)))
    end:
seq(a(n), n=1..40);  # Alois P. Heinz, Jan 15 2024

Mathematica

NestList[#+FromDigits[Sort[IntegerDigits[#]]]&,1,40] (* Harvey P. Dale, Jul 24 2016 *)

Python

from itertools import islice
def agen(an=1): # generator of terms
    while True: yield an; an = an + int("".join(sorted(str(an))))
print(list(islice(agen(), 100))) # Michael S. Branicky, Jan 15 2024

Formula

a(n+1) = A070196(a(n)). - Reinhard Zumkeller, Apr 03 2015