# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a374527 Showing 1-1 of 1 %I A374527 #18 Jul 29 2024 06:20:59 %S A374527 1,21,85,151,227,341,1365,5461,14563,21845,87381,349525,932067, %T A374527 1398101,5592405,22369621,26512143,39768215,59652323,89478485, %U A374527 357913941,1431655765,3817748707,5726623061 %N A374527 Odd numbers whose Collatz trajectory is a Sidon sequence. %C A374527 For more information see A375006. %o A374527 (Python) %o A374527 from itertools import count, islice %o A374527 def A374527_gen(startvalue=1): # generator of terms >= startvalue %o A374527 s = max(startvalue,1) %o A374527 for n in count(s+(s&1^1),2): %o A374527 t, a, c = [n], n, set() %o A374527 while a > 1: %o A374527 a = 3*a+1 if a&1 else a>>1 %o A374527 for p in t: %o A374527 if (b:=p+a) in c: %o A374527 break %o A374527 c.add(b) %o A374527 else: %o A374527 t.append(a) %o A374527 continue %o A374527 break %o A374527 else: %o A374527 yield n %o A374527 A374527_list = list(islice(A374527_gen(),10)) # _Chai Wah Wu_, Jul 27 2024 %Y A374527 Odd terms of A375006. %K A374527 nonn,hard,more %O A374527 1,2 %A A374527 _Markus Sigg_ and _Hugo Pfoertner_, Jul 27 2024 %E A374527 a(23)-a(24) from _Chai Wah Wu_, Jul 29 2024 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE