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%I #9 May 15 2017 15:24:55
%S 1,3,13,313,13313,31313313,1331331313313,313133131331331313313,
%T 1331331313313313133131331331313313,
%U 3131331313313313133131331331313313313133131331331313313
%N Define the first two terms to be 1 and 3. All the other terms are obtained by concatenating the two previous terms.
%H Harvey P. Dale, <a href="/A113526/b113526.txt">Table of n, a(n) for n = 1..16</a>
%e The third term is 13 which is obtained by concatenating the two previous terms 1 and 3.
%t a[1] = 1; a[2] = 3; a[n_] := FromDigits@ Join[IntegerDigits@a[n - 2], IntegerDigits@a[n - 1]]; Array[a, 10] (* _Robert G. Wilson v_ *)
%t nxt[{a_,b_}]:={b,FromDigits[Join[Flatten[IntegerDigits/@{a,b}]]]}; NestList[nxt,{1,3},10][[All,1]] (* _Harvey P. Dale_, May 15 2017 *)
%Y Cf. A008352.
%K base,nonn
%O 1,2
%A _Parthasarathy Nambi_, Jan 12 2006
%E More terms from _Robert G. Wilson v_, Jan 18 2006