%I A141551
%S A141551 1,2,4,6,12,24,36,48,60,72,84,96,108,120,132,144,156,180,192,204,228,240,
%T A141551 252,276,288,300,324,348,360,372,396,444,468,480,492,516,564,576,588,600,
%U A141551 612,636,684,708,720,732,804,828,840,852,876,900,948,960,972,996,1044,
               1068
%N A141551 Numbers n with property that if d divides n, then tau(tau(d)) also divides 
               n.
%C A141551 tau() = A000005().
%p A141551 with(numtheory); isA141551 := proc(n) local dvs,d; dvs := divisors(n) 
               ; for d in dvs do if not tau(tau(d)) in dvs then RETURN(false): fi; 
               od: RETURN(true); end:
%p A141551 t1:=[]; for n from 1 to 60000 do if isA141551(n) then t1:=[op(t1),n]; 
               fi; od:
%Y A141551 Cf. A141586.
%Y A141551 Sequence in context: A018894 A056795 A141420 this_sequence A094348 A002182 
               A077006
%Y A141551 Adjacent sequences: A141548 A141549 A141550 this_sequence A141552 A141553 
               A141554
%K A141551 nonn
%O A141551 1,2
%A A141551 N. J. A. Sloane (njas(AT)research.att.com), Sep 12 2008