OFFSET
1,1
COMMENTS
Self-describing numbers: between two digits "d" there are d digits.
a(n) has either 0 or 2 instances of any digit, hence even number of digits, and in fact the number of digits of a(n) == 0 or 2 or 6 (mod 8).
"weaker" means that when the smallest digit is x, all digits from x to the largest digit must be present.
The smallest digit x could be any value, but it turns out the biggest is x = 3 with 28 terms in total.
This sequence has 3390 terms. The largest term is 867315136875420024.
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..3390
EXAMPLE
41312432 is a term since both 4's are separated by four digits, the 1's by one, the 3's by three, the 2's by two. Every digit from 1 to 4 is present.
PROG
(Python)
def afull(): # SL() is in A108116
alst = []
for d in range(1, 11):
for b in range(11-d):
dset = ("0123456789")[b:b+d]
s = [0 for _ in range(2*d)]
for an in sorted(SL(dset, s)):
alst.append(an)
return sorted(alst)
print(afull()[:22]) # Michael S. Branicky, Oct 14 2022
CROSSREFS
KEYWORD
nonn,base,easy,fini,full
AUTHOR
Marc Morgenegg, Oct 14 2022
EXTENSIONS
More terms from David A. Corneth, Oct 14 2022
STATUS
approved