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%I #9 May 21 2016 22:44:25
%S 1,21,987,1602160116001599,
%T 350301931135697350301931135696350301931135695350301931135694350301931135693
%N a(1) = 1, a(n+1) = least multiple of a(n) which is a concatenation in descending order of n+1 successive positive integers.
%C In A112364 also 0 is admitted (see a(2) = 10) while in this sequence is not.
%e a(2) / a(1) = 21;
%e a(3) / a(2) = 47;
%e a(4) / a(3) = 1623262528877;
%e a(5) / a(4) = 218643522352760739495083693166843046731892253220075561675507.
%p P:=proc(q) local a,b,k,j,n; a:=1; print(a);
%p for k from 2 to q do for n from 1 to q do
%p b:=n; for j from 1 to k-1 do b:=(n+j)*10^(ilog10(b)+1)+b; od;
%p if type(b/a,integer) then a:=b; print(b); break; fi; od; od; end: P(10^9);
%Y Cf. A112363, A112364.
%K nonn,base
%O 1,2
%A _Paolo P. Lava_, May 19 2016
%E a(5) from _Giovanni Resta_, May 19 2016