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Knife numbers (third version): n=concat(a,b) is divisible by a+b; a>0, b may have leading zeros.

3

`%I #9 Jan 02 2023 12:30:50
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`%S 10,12,18,20,21,24,27,30,36,40,42,45,48,50,54,60,63,70,72,80,81,84,90,
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`%T 100,102,105,108,110,120,126,130,132,140,144,147,150,160,162,168,170,
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`%U 180,189,190,198,200,201,204,207,209,210,216,220,230,231,240,243,250,260,264,270,280,288,290,297,300,306,308,310,320,324,330,340
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`%N Knife numbers (third version): n=concat(a,b) is divisible by a+b; a>0, b may have leading zeros.
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`%C See subsequences A247624, A247625 and A247627 for more restrictive definitions, excluding, e.g., leading zeros in b.
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`%H E. Angelini, <a href="http://list.seqfan.eu/oldermail/seqfan/2014-September/013661.html">Knife numbers</a>.
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`%o (PARI) is(n)=n&&for(k=1,#Str(n)-1,n%([1,1]*divrem(n,10^k))||return(1))
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`%K nonn,base
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`%O 1,1
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`%A _M. F. Hasler_ and _Eric Angelini_, Sep 21 2014
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