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%I #4 Dec 05 2013 19:55:57
%S 1,21,3213,4321485,5432106645,6543211466594880,
%T 76543214032699698271680,8765432112983964669342594296640,
%U 9876543213798659527816605720220081111680
%N a(1) = 1, a(n) for n > 1 is the smallest multiple of a(n-1) that begins with the reverse concatenation from n to 1.
%e For n = 3 we have a(n-1) = a(2) = 21; 153*21 = 3213 is the smallest multiple of a(2) that begins with 321, so a(3) = 3213.
%o (PARI) {print1(a=1,","); for(n=2,9,k=floor(log(a)/log(10))+1; v=Str(1); for(i=2,n, v=concat(Str(i),v)); s=eval(v); t=s+1; m=floor(log(s)/log(10))+1; d=k-m; s=s*10^d; t=t*10^d; b=1; j=d; while(b>0,q=floor(s/a); while(b>0&&(p=q*a)<t,if(p>=s,print1(p,","); b=0,q++)); s=10*s; t=10*t); a=p)}
%Y Cf. A078296, A078396, A078397.
%K base,nonn
%O 1,2
%A _Amarnath Murthy_, Nov 26 2002
%E Edited and extended by _Klaus Brockhaus_, Dec 06 2002
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