OFFSET
1,2
COMMENTS
See A066272 for definition of anti-divisor.
EXAMPLE
40 is a term since its prime factors are {2, 2, 2, 5} and its anti-divisors are {3, 9, 16, 27}.
MATHEMATICA
atd[n_] := Count[Flatten[Quotient[#, Rest[Select[Divisors[#], OddQ]]] & /@ (2 n + Range[-1, 1])], Except[1]]; Select[Range[1760], PrimeOmega[#] == atd[#] &] (* Jayanta Basu, Jul 08 2013 *)
PROG
(PARI) {for(n=1, 1800, v1=[]; v2=[]; v3=[]; ds=divisors(2*n-1); for(k=2, matsize(ds)[2]-1, if(ds[k]%2>0, v1=concat(v1, ds[k]))); ds=divisors(2*n); for(k=2, matsize(ds)[2]-1, if(ds[k]%2>0, v2=concat(v2, ds[k]))); ds=divisors(2*n+1); for(k=2, matsize(ds)[2]-1, if(ds[k]%2>0, v3=concat(v3, ds[k]))); v=vecsort(concat(v1, concat(v2, v3))); if(matsize(v)[2]==bigomega(n), print1(n, ", ")))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Aug 30 2002
EXTENSIONS
Edited and extended by Klaus Brockhaus, Sep 02 2002
STATUS
approved