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A374527
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Odd numbers whose Collatz trajectory is a Sidon sequence.
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2
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1, 21, 85, 151, 227, 341, 1365, 5461, 14563, 21845, 87381, 349525, 932067, 1398101, 5592405, 22369621, 26512143, 39768215, 59652323, 89478485, 357913941, 1431655765, 3817748707, 5726623061
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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LINKS
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PROG
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(Python)
from itertools import count, islice
def A374527_gen(startvalue=1): # generator of terms >= startvalue
s = max(startvalue, 1)
for n in count(s+(s&1^1), 2):
t, a, c = [n], n, set()
while a > 1:
a = 3*a+1 if a&1 else a>>1
for p in t:
if (b:=p+a) in c:
break
c.add(b)
else:
t.append(a)
continue
break
else:
yield n
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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