The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #10 Dec 23 2024 14:53:44
%S 12,18,21,24,27,36,42,45,48,54,63,72,81,84,105,108,110,126,132,144,
%T 147,162,168,189,198,216,220,231,243,264,288,297,324,330,396,405,414,
%U 418,429,432,440,462,486,495,510,528,540,550,567,594,612,616,621,627,648,660,693,714,726,729,756,770,792,810,814,816,825,828,836
%N Knife numbers (first version): n=concat(a,b) is divisible by a+b; a,b>0.
%C It is understood that b does not have leading zeros.
%C This is a subsequence of A247625, A247626 and A247627 which allow b to have leading zeros or to be zero.
%H E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2014-September/013661.html">Knife numbers</a>.
%o (PARI) is(n,u=[1,1])=n&&for(k=1,#Str(n)-1,n%(u*divrem(n,10^k))==0&&(n%10^k>=10^(k-1))&&return(1))
%K nonn,base
%O 1,1
%A _M. F. Hasler_ and _Eric Angelini_, Sep 21 2014