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%I #8 Jan 02 2023 12:30:50
%S 10,12,18,20,21,24,27,30,36,40,42,45,48,50,54,60,63,70,72,80,81,84,90,
%T 100,105,108,110,120,126,130,132,140,144,147,150,160,162,168,170,180,
%U 189,190,198,200,210,216,220,230,231,240,243,250,260,264,270,280,288,290,297,300,310,320,324,330,340,350,360,370,380,390,396,400
%N Knife numbers (fourth version): n=concat(a,b) is divisible by a+b; a>0 and b may be zero but not have leading zeros.
%C Sequence A247624 is a subsequence, and A247626 contains this as a subsequence, while A247625 is a different variant (with the same inclusion properties).
%H M. F. Hasler in reply to E. Angelini, <a href="http://list.seqfan.eu/oldermail/seqfan/2014-September/013672.html">Re: Knife numbers</a>, SeqFan list, Sep 21 2014.
%e All n = 10k = concat(k,0) are in this sequence, because k+0 divides n.
%e However, e.g., 102 is not included since the decomposition in 1+02 is not allowed (and 10+2 does not divide 102).
%o (PARI) is(n)=n&&for(k=1,#Str(n)-1,n%([1,1]*divrem(n,10^k))==0&&(k==1||n%10^k>=10^(k-1))&&return(1))
%K nonn,base
%O 1,1
%A _M. F. Hasler_ and _Eric Angelini_, Sep 21 2014