%I A133468
%S A133468 1,2,9,150,38505,2523490710,10838310072981296745
%N A133468 A080814 complemented, then interpreted as binary and then re-expressed 
               in decimal form (e.g. "1221" = "0110"). Alternately, view as A080814 
               with "1" mapped to "1" and "2" mapped to "0".
%F A133468 The "~" operator, as used here, represents binary inversion/complement. 
               a(0) = 1 a(n) = a(n-1) followed by ~a(n-1)
%o A133468 function invert(string s) returns string { s.replace("0","2"); s.replace("1",
               "0"); s.replace("2","1"); } function f(int n) returns string { if 
               (n==0) return "1"; return concat(f(n-1),invert(f(n-1)); //Blatant 
               opportunity for optimization } function a(int n) returns int { return 
               f(n).InterpretAsBinary(); }
%Y A133468 Cf. A080814, A080815, A048707.
%Y A133468 Sequence in context: A110860 A050995 A117116 this_sequence A081459 A038843 
               A053294
%Y A133468 Adjacent sequences: A133465 A133466 A133467 this_sequence A133469 A133470 
               A133471
%K A133468 nonn
%O A133468 0,2
%A A133468 Dan Reif (integer-sequences(AT)angelfaq.com), Nov 28 2007, corrected 
               Nov 30 2007