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%I #21 Jan 18 2019 01:34:53
%S 1,1,1,37,1591,3010043,159102273287149,65512700765296656417780781597,
%T 37123863767001438636742442904988504233588432218805926927199,
%U 3712386376700143863674244290498850423358843221880592692719912374621255667146212247480968329501411196144072935308975733
%N a(1)=1, a(2)=1; for n > 2, a(n) is the largest proper divisor of the concatenation of terms a(1) through a(n-1).
%C This sequence is nondecreasing. Indeed, let c(n) be the concatenation of the first n terms of this sequence and d(n) the number of decimal digits of a(n). For n > 2, a(n) divides c(n-1), so a(n) is a proper divisor of c(n-1)*10^d(n) + a(n) = c(n), and thus a(n) <= a(n+1). - _Danny Rorabaugh_, Nov 27 2018
%C a(11) is too large to show in the Data section. It is
%C 3712386376700143863674244290498850423358843221880592692719912374621255667\
%C 1462122474809683295014111961440729353089757331237462125566714621224748096\
%C 8329501411196144072935308975733041248737518890487374158269894431671370653\
%C 81357645102991911.
%t FromDigits /@ Nest[Append[#, IntegerDigits@ Divisors[FromDigits[Join @@ #]][[-2]] ] &, {{1}, {1}}, 8] (* _Michael De Vlieger_, Nov 26 2018 *)
%Y Cf. A322098.
%K nonn,base
%O 1,4
%A _John Mason_, Nov 26 2018
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