OFFSET
1,1
COMMENTS
See A066272 for definition of anti-divisor.
LINKS
Jon Perry, The Anti-Divisor
Jon Perry, The Anti-divisor [Cached copy]
Jon Perry, The Anti-divisor: Even More Anti-Divisors [Cached copy]
MATHEMATICA
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[ # ]] == 12 & ]
nd[n_]:=Count[Range[2, n-1], _?(Abs[Mod[n, #]-#/2]<1&)]; Select[Range[ 12500], nd[#]==12&] (* Harvey P. Dale, Jul 11 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jan 02 2002
STATUS
approved