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A367600
Numbers that are not the comma-successor of any number.
3
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 30, 31, 32, 37, 38, 39, 40, 41, 42, 43, 49, 50, 51, 52, 53, 54, 60, 62, 63, 64, 65, 70, 74, 75, 76, 80, 86, 87, 90, 98, 200, 300, 400, 500, 600, 700, 800, 900, 2000, 3000, 4000, 5000, 6000, 7000
OFFSET
1,2
COMMENTS
These are the positive integers that do not appear in A367338.
All terms > 98 are of the form c*10^i for i >= 2 and 2 <= c <= 9; see proof in links. - Michael S. Branicky, Nov 28 2023
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..110 (all terms < 10^9)
Eric Angelini, Michael S. Branicky, Giovanni Resta, N. J. A. Sloane, and David W. Wilson, The Comma Sequence: A Simple Sequence With Bizarre Properties, arXiv:2401.14346, Youtube
Michael S. Branicky, Comma-Predecessor Theorem
PROG
(Python)
from itertools import count, islice
def A367338(n):
nn = n + 10*(n%10)
return next((nn+y for y in range(1, 10) if str(nn+y)[0] == str(y)), -1)
def agen():
A367338_set = set()
for n in count(1):
A367338_set.add(A367338(n))
if n not in A367338_set:
yield n
# A367338_set.discard(n-100) # uncomment if memory is an issue
print(list(islice(agen(), 86))) # Michael S. Branicky, Nov 28 2023
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Nov 23 2023
STATUS
approved