cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A092680 Numbers of the form 3*2^k with a single anti-divisor.

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%I A092680 #29 Feb 14 2025 08:26:15
%S A092680 3,6,96,393216
%N A092680 Numbers of the form 3*2^k with a single anti-divisor.
%C A092680 See A066272 for definition of anti-divisor.
%C A092680 If it exists, a(5) > 3*2^(1000). See A092679. - _J.W.L. (Jan) Eerland_, Nov 13 2022
%F A092680 a(n) = 3*2^A092679(n).
%F A092680 a(n) = 3*2^(A181490(n)-1) = (A181491(n)+1)/2 = (A181492(n)-1)/2. - _Max Alekseyev_, Feb 14 2025
%o A092680 (Python)
%o A092680 from itertools import count, islice
%o A092680 from sympy.ntheory.factor_ import antidivisor_count
%o A092680 def A092680_gen(): return filter(lambda n: antidivisor_count(n)==1,(3*2**k for k in count(0)))
%o A092680 A092680_list = list(islice(A092680_gen(),4)) # _Chai Wah Wu_, Jan 04 2022
%Y A092680 Cf. A066272, A066466, A092679, A181490, A181491, A181492.
%K A092680 nonn,hard,more
%O A092680 1,1
%A A092680 _Lior Manor_, Mar 03 2004