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 A129751 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 and the set construct contents are ordered by increasing cardinality. 1
 0, 102, 101022, 101021010222, 101021010221010210102222, 101021010221010210102221010210102210102101022222, 101021010221010210102221010210102210102101022221010210102210102101022210102101022101021010222222 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS PlanetMath, von Neumann integer EXAMPLE a(0)=0, a(1)={0}=102, a(2)={0,{0}}=101022, etc. MAPLE 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: CROSSREFS Cf. A129754. Sequence in context: A030512 A097725 A353142 * A225993 A237432 A279242 Adjacent sequences:  A129748 A129749 A129750 * A129752 A129753 A129754 KEYWORD easy,nonn,base AUTHOR I.N. Galidakis (jgal(AT)ath.forthnet.gr), May 14 2007 STATUS approved

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Last modified May 21 03:13 EDT 2022. Contains 353886 sequences. (Running on oeis4.)