OFFSET
1,3
COMMENTS
10 is obviously the first integer not present in the sequence as 1 > 0.
EXAMPLE
a(10) = 9 and a(11) = 13 sum up to 22: the three numbers have digits in nondecreasing order;
a(11) = 13 and a(12) = 11 sum up to 24 (same property);
a(12) = 11 and a(13) = 12 sum up to 23 (same property); etc.
PROG
(Python)
def nondec(n): s = str(n); return s == "".join(sorted(s))
def aupton(terms):
alst = [0]
for n in range(2, terms+1):
an = 1
while True:
while an in alst: an += 1
if nondec(an) and nondec(alst[-1]+an): alst.append(an); break
else: an += 1
return alst
print(aupton(74)) # Michael S. Branicky, Mar 07 2021
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Mar 07 2021
STATUS
approved