A033863 Least number of Sort-then-add persistence n.

1, 10, 65, 64, 175, 98, 240, 325, 302, 387, 198, 180, 550, 806, 855, 486, 351, 315, 944, 2428, 2204, 3172, 1793, 1316, 937, 2775, 1815, 1461, 2541, 9378, 13327, 9638, 8149, 6581, 46965, 23487, 12198, 10599, 10920, 52345, 48788, 180666, 174870, 291119, 155563, 915443

Offset: 0

Author

David W. Wilson

Keywords

• nonn
• base

Links

• Michael S. Branicky, Table of n, a(n) for n = 0..100
• Sean A. Irvine, Java program (github).
• Eric Weisstein's World of Mathematics, Sort-Then-Add Sequence.

Crossrefs

Cf. A033909, A033908.

Programs

Python

from itertools import count, islice
def agen(LIMIT):
    adict, n = dict(), 0
    for k in count(1):
        c, m = 0, k
        while c <= LIMIT and m != (s:=int("".join(sorted(str(m))))):
            m += s; c += 1
        if c not in adict:
            adict[c] = k
            while n in adict and n <= LIMIT: yield adict[n]; n += 1
            if n > LIMIT: return
print(list(agen(40))) # Michael S. Branicky, Jan 16 2024

Extensions

a(44)-a(45) from Sean A. Irvine, Jul 26 2020