A097569 Right-truncatable Harshad numbers (zeros not permitted).

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

Offset

1,2

Comments

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.

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: A334416 A217973 A097518 * A308561 A095160 A356350

Adjacent sequences: A097566 A097567 A097568 * A097570 A097571 A097572

Keyword

base,nonn,fini,full

Author

Jason Earls, Aug 28 2004

Status

approved