OFFSET
1,2
COMMENTS
This is not A276766, though the first 63 terms are the same.
LINKS
Carole Dubois, Table of n, a(n) for n = 1..5000
EXAMPLE
The four digits of a(11) = 23 and a(12) = 14 are distinct;
the four digits of a(12) = 14 and a(13) = 20 are distinct;
but so are also the successive digits 3,1,4,2 visible in 23, 14, 20;
the four digits of a(13) = 20 and a(14) = 13 are distinct;
the four digits of a(14) = 13 and a(15) = 24 are distinct;
but so are also the successive digits 0,1,3,2 visible in 20,13,24; etc.
PROG
(Python)
from itertools import islice
def ok(s): return all(len(set(s[i:i+4]))==4 for i in range(len(s)-3))
def agen(): # generator of terms
aset, s, k, mink = {1}, "xy1", 1, 2
while True:
yield k
k, avoid = mink, set(s)
while k in aset or not ok(s + str(k)): k += 1
aset.add(k)
s = (s + str(k))[-4:]
while mink in aset: mink += 1
print(list(islice(agen(), 79))) # Michael S. Branicky, Jun 30 2022
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Feb 03 2020
STATUS
approved