%I A121805
%S A121805 1,12,35,94,135,186,248,331,344,387,461,475,530,535,590,595,651,667,
%T A121805 744,791,809,908,997,1068,1149,1240,1241,1252,1273,1304,1345,1396,
%U A121805 1457,1528,1609,1700,1701,1712,1733,1764,1805,1856,1917,1988,2070
%N A121805 The "commas" sequence: a(1) = 1; for n > 1, let x be the least significant 
               digit of a(n-1); then a(n) = a(n-1) + x*10 + y where y is the most 
               significant digit of a(n) and is the smallest such y, if such a y 
               exists. If no such y exists, stop.
%C A121805 The sequence contains exactly 2137453 terms, with a(2137453)=99999945. 
               The next term does not exist. - Edwin Clark, Dec 11 2006
%C A121805 It is remarkable that the sequence persists for so long. - N. J. A. Sloane 
               (njas(AT)research.att.com), Dec 15 2006
%D A121805 E. Angelini, "Jeux de suites", in Dossier Pour La Science, pp. 32-35, 
               Volume 59 (Jeux math'), April/June 2008, Paris.
%H A121805 Zak Seidov, <a href="b121805.txt">Table of n, a(n) for n = 1..1001</a>
%H A121805 Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/
               Commas.htm">(No title)</a>
%e A121805 E.g. a(6) = 186 and a(7) = 248 = 186 + 62
%e A121805 Sequence...:.1,.12,.35,.94,.135,.186,.248,.331,.344,.387,.461,.475,.530,
               .535,.590,....
%e A121805 Differences:..11..23..59..41...51...62...83...13...43...74...14...55...05...55.....
%p A121805 (Maple program from Edwin Clark): digits:=n->ListTools:-Reverse(convert(n,
               base,10)):
%p A121805 nextK:=proc(K) local i,L; for i from 0 to 9 do L:=K+digits(K)[ -1]*10+i; 
               if i = digits(L)[1] then return L; fi; od; FAIL; end:
%p A121805 a:=proc(n) option remember: if n = 1 then return 1; fi; return nextK(a(n-1)); 
               end:
%Y A121805 Cf. A139284.
%Y A121805 Sequence in context: A142074 A102085 A058968 this_sequence A103472 A009649 
               A007794
%Y A121805 Adjacent sequences: A121802 A121803 A121804 this_sequence A121806 A121807 
               A121808
%K A121805 nonn,base,fini,nice
%O A121805 1,2
%A A121805 Eric Angelini (Eric.Angelini(AT)kntv.be), Dec 11 2006
%E A121805 More terms from Zak Seidov, Dec 11 2006