%I #10 Feb 23 2024 01:09:37
%S 137,143,157,158,175,193,202,238,262,270,275,280,283,293,305,319,337,
%T 346,367,388,390,391,402,403,412,418,428,435,446,451,455,465,468,488,
%U 490,493,494,501,507,508,525,533,540,542,562,570,580,587,588,592,595
%N Numbers having just eleven anti-divisors.
%C See A066272 for definition of anti-divisor.
%H Jon Perry, <a href="http://www.users.globalnet.co.uk/~perry/maths/antidivisor.htm">The Anti-Divisor</a>
%H Jon Perry, <a href="/A066272/a066272a.html">The Anti-divisor</a> [Cached copy]
%H Jon Perry, <a href="/A066272/a066272.html">The Anti-divisor: Even More Anti-Divisors</a> [Cached copy]
%t antid[n_] := Select[ Union[ Join[ Select[ Divisors[2n - 1], OddQ[ # ] && # != 1 & ], Select[ Divisors[2n + 1], OddQ[ # ] && # != 1 & ], 2n/Select[ Divisors[ 2*n], OddQ[ # ] && # != 1 &]]] }, # < n & ]]; Select[ Range[10^4], Length[ antid[ # ]] == 11 & ]
%Y Cf. A066272.
%K nonn
%O 1,1
%A _Robert G. Wilson v_, Jan 02 2002