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:
MATHEMATICA
Join[{0}, Map[FromDigits, NestList["1"<>StringTake[#, {2, -2}]<>#<>"2"&, "102", 7]]] (* Paolo Xausa, Nov 22 2023 *)
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
I.N. Galidakis (jgal(AT)ath.forthnet.gr), May 14 2007
STATUS
approved