%I A129754
%S A129754 11,278,202040,107371882880,30324991112647875920960,
%T A129754 2418916677393691552133618294938847890243982720,
%U A129754 15390805926573768302084260548391044837412074858741153833336080616936611834819590898337488640
%N A129754 The natural numbers represented by their set theoretic Von Neumann construction, 
               where the empty set is replaced by '0', the left set bracket '{' 
               is replaced by 1, the right bracket '}' is replaced by 2, the set 
               construct contents are ordered by increasing cardinality and the 
               final number is interpreted in base 3.
%H A129754 I.N. Galidakis, <a href="http://ioannis.virtualcomposer2000.com">Home 
               Page</a>
%F A129754 S(n)=n union {n}
%e A129754 a(0)=0=0[3]=0, a(1)={0}=102[3]=11, a(2)={0,{0}}=101022[3]=278, etc
%p A129754 N:=proc(n) local i,s,l,r,data; s:=`0`;l:=`1`;r:=`2`; if n>0 then for 
               i from 1 to n-1 do s:=cat(s,l,s,r); od; s:=cat(l,s,r); fi; data:=sscanf(s,
               `%d`); RETURN(data[1]); end: b3tob10:=proc(n) local i,nl,sl,suma; 
               if n=0 then suma:=0; else sl:=convert(n,base,10); nl:=convert(sl,
               base,3,10); suma:=sum(nl[i]*10^(i-1),i=1..nops(nl)); fi; RETURN(suma); 
               end: for n from 0 to 7 do b3tob10(N(n)); od;
%Y A129754 Cf. A129751.
%Y A129754 Sequence in context: A160195 A062210 A049080 this_sequence A103547 A166182 
               A064758
%Y A129754 Adjacent sequences: A129751 A129752 A129753 this_sequence A129755 A129756 
               A129757
%K A129754 easy,nonn
%O A129754 0,1
%A A129754 I.N. Galidakis (jgal(AT)ath.forthnet.gr), May 14 2007