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.

A092679 Numbers k such that 3*2^k has only one anti-divisor.

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%I A092679 #28 Feb 14 2025 08:26:06
%S A092679 0,1,5,17
%N A092679 Numbers k such that 3*2^k has only one anti-divisor.
%C A092679 Next term should be greater than 3*10^6 (cf. A181490).
%C A092679 See A066272 for definition of anti-divisor.
%F A092679 A092680(n) = 3*2^a(n).
%F A092679 a(n) = A181490(n) - 1. - _Max Alekseyev_, Feb 14 2025
%o A092679 (Python)
%o A092679 A092679 = [i for i,n in enumerate(map(lambda x:3*2**x,range(20))) if len([d for d in range(2,n,2) if n%d and not 2*n%d]+[d for d in range(3,n,2) if n%d and 2*n%d in [d-1,1]])==1] # _Chai Wah Wu_, Aug 09 2014
%Y A092679 Cf. A066466, A092680, A181490.
%K A092679 nonn,hard,more
%O A092679 1,3
%A A092679 _Lior Manor_, Mar 03 2004