

A097569


Righttruncatable Harshad numbers (zeros not permitted).


2



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, 243, 247, 364, 423, 481, 486, 846, 2478, 8463, 24786
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

Harshad numbers in which repeatedly deleting the rightmost digit gives a Harshad at every step until a single digit Harshad remains. Sequence is finite with 24786 being the last term.
24786 can be proved to be the last term by a genetic approach (constructing the whole tree).  Carlos Rivera, Sep 19 2004


LINKS

Table of n, a(n) for n=1..35.


MATHEMATICA

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 *)


CROSSREFS

Cf. A005349.
Sequence in context: A114440 A217973 A097518 * A095160 A288528 A200372
Adjacent sequences: A097566 A097567 A097568 * A097570 A097571 A097572


KEYWORD

base,nonn,fini,full


AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Aug 28 2004


STATUS

approved



