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A369148
In the MIU formal system, total number (including duplicates) of strings up to n steps distant from the MI string.
1
1, 3, 6, 12, 28, 88, 444, 3671, 47981, 976631, 29554002, 1326494644
OFFSET
0,2
COMMENTS
See A368946 for the description of the MIU formal system.
REFERENCES
Douglas R. Hofstadter, Gödel, Escher, Bach: an Eternal Golden Braid, Basic Books, 1979, pp. 33-41.
FORMULA
a(n) >= A331536(n+1).
MATHEMATICA
MIUStepW3[s_] := Flatten[Map[{If[StringEndsQ[#, "1"], # <> "0", Nothing], # <> #, StringReplaceList[#, {"111" -> "0", "00" -> ""}]}&, s]];
With[{rowmax = 9}, Accumulate[Map[Length, NestList[MIUStepW3, {"1"}, rowmax]]]]
CROSSREFS
Cf. A331536 (without duplicates), A368946, A369173 (all MIU strings).
Partial sums of A368947.
Sequence in context: A018011 A025208 A245774 * A049941 A219634 A252696
KEYWORD
nonn,hard,more
AUTHOR
Paolo Xausa, Jan 14 2024
STATUS
approved