Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #7 Jan 02 2023 12:30:50
%S 12,18,21,24,27,36,42,45,48,54,63,72,81,84,102,105,108,110,126,132,
%T 144,147,162,168,189,198,201,204,207,209,216,220,231,243,264,288,297,
%U 306,308,324,330,396,402,405,407,408,414,418,429,432,440,462,486,495,504,506,510,528,540,550,567,594,603,605,612,616,621,627,648
%N Knife numbers (second version): n=concat(a,b) is divisible by a+b; a>0; b must not have leading zeros.
%C Here, b must not have leading zeros but may be zero, in contrast to the subsequence A247624 and the alternate variant A247627. Sequence A247626 is less restrictive, allowing leading zeros in b.
%H E. Angelini, <a href="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)&&return(1))
%K nonn,base
%O 1,1
%A _M. F. Hasler_ and _Eric Angelini_, Sep 21 2014