OFFSET
1,1
COMMENTS
Numbers n such that d(n)=d(n-d(n)).
MATHEMATICA
sndQ[n_]:=Module[{dn=DivisorSigma[0, n]}, dn==DivisorSigma[0, n-dn]]; Select[ Range[250], sndQ] (* Harvey P. Dale, Mar 05 2014 *)
PROG
(PARI) for(n=3, 1000, if(numdiv(n)==numdiv(n-numdiv(n)), print1(n, ", ")))
CROSSREFS
KEYWORD
dead
AUTHOR
Juri-Stepan Gerasimov, Nov 20 2010
STATUS
approved