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%I #12 Dec 08 2018 04:10:40
%S 1,2,3,4,5,6,7,8,9,12,18,21,24,27,36,42,45,48,54,63,72,81,84,126,216,
%T 243,247,364,423,481,486,846,2478,8463,24786
%N Right-truncatable Harshad numbers (zeros not permitted).
%C Harshad numbers in which repeatedly deleting the rightmost digit gives a Harshad number at every step until a single-digit Harshad number remains. Sequence is finite with 24786 being the last term.
%C 24786 can be proved to be the last term by a genetic approach (constructing the whole tree). - _Carlos Rivera_, Sep 19 2004
%t harQ[n_]:=Module[{idn=IntegerDigits[n]},!MemberQ[idn,0]&&Divisible[n, Total[ idn]]]; rtQ[n_]:=Module[{idn=IntegerDigits[n],c}, c=Table[ FromDigits[ Take[ idn,i]],{i,Length[idn]}];And@@(harQ/@c)]; Select[ Range[25000],rtQ] (* _Harvey P. Dale_, Oct 07 2013 *)
%Y Cf. A005349.
%K base,nonn,fini,full
%O 1,2
%A _Jason Earls_, Aug 28 2004
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