A033861 Sort-then-add sequence: a(1) = 316, a(n+1) = a(n) + sort(a(n)).

316, 452, 697, 1376, 2743, 5090, 5149, 6608, 7276, 9953, 13552, 25907, 28486, 53174, 66631, 80297, 83086, 86774, 133552, 256907, 282586, 508274, 532852, 756410, 770977, 848756, 1305544, 1439999, 2789998, 5578997, 11156896

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Comments

316 is almost certainly the least starter not leading to a sorted element.

Examples

			a(1) = 316, a(2) = a(1)+sort(a(1)) = 316 + 136 = 452, a(3) = a(2) + sort(a(2)) = 452 + 245 = 697. - _Indranil Ghosh_, Jan 29 2017
		

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Sort-Then-Add Sequence.

Crossrefs

Cf. A033860, A033862, A033863.

Programs

Mathematica

NestList[#+FromDigits[Sort[IntegerDigits[#]]]&,316,40] (* Harvey P. Dale, Jan 28 2013 *)

Python

A033861_list = [316]
for i in range(100):
    x = A033861_list[-1]
    A033861_list.append(x+int(''.join(sorted(str(x))))) # Chai Wah Wu, Feb 07 2020