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A090335 Smallest number with exactly n distinct prime factors such that in binary representation the divisors >1 form a prefix code. 2

%I #9 Dec 16 2021 07:37:45

%S 1,2,33,2093,239723,29918977,17597346187,17155385292853,

%T 10633323942990239,15790705299133143889

%N Smallest number with exactly n distinct prime factors such that in binary representation the divisors >1 form a prefix code.

%C Conjecture: the sequence is defined for all n.

%C a(10) <= 281594003343201014885689. - _David Wasserman_, Dec 13 2005

%F a(n) = Min{k: A090330(k)=0 and A001221(k)=n}.

%e a(3) = 2093 = 7*13*23 with divisors >1: 7, 13, 23, 91, 161, 299 and 2093, which are prefix-free in binary: 111, 1101, 10111, 1011011, 10100001, 100101011 and 100000101101.

%Y Cf. A088862, A090332.

%K nonn,base,more

%O 1,2

%A _Reinhard Zumkeller_, Nov 26 2003

%E More terms from _David Wasserman_, Dec 13 2005

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)