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A122954
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a(1) = 1. a(n) = number of earlier terms which, when written in binary, are substrings of binary n.
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2
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1, 1, 2, 3, 3, 5, 4, 4, 5, 5, 8, 7, 8, 6, 5, 7, 7, 5, 7, 10, 9, 11, 15, 10, 9, 13, 13, 12, 17, 11, 9, 7, 7, 8, 11, 8, 13, 11, 16, 16, 15, 10, 17, 18, 18, 21, 22, 15, 15, 14, 12, 19, 18, 19, 24, 22, 20, 24, 25, 21, 25, 17, 14, 11, 11, 11, 13, 12, 17, 16, 21, 15, 11, 19, 26, 17, 23, 22, 24
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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COMMENTS
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First occurrence of k: 1, 3, 4, 7, 6, 14, 12, 11, 21, 20, 22, 28, 26, 50, 23, 39, 29, 44, 52, 57, 46, 47, 77, 55, 59, ...
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LINKS
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EXAMPLE
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Binary a(1) = 1, binary a(2) = 1, binary a(3) = 10, binary a(7) = 100 and binary a(8) = 100 are all substrings of binary 9 = 1001. So a(9) = 5.
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MAPLE
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A[1]:= 1:
S[1]:= "1":
for n from 2 to 100 do
B:= convert(convert(n, binary), string);
A[n]:= nops(select(t -> SearchText(S[t], B)>0, [$1..n-1]));
S[n]:= convert(convert(A[n], binary), string);
od:
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MATHEMATICA
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f[ s_ ] := Append[ s, Length@ Select[ s, StringPosition[ ToString@ FromDigits@ IntegerDigits[ Length@s + 1, 2 ], ToString@ FromDigits@ IntegerDigits[ #, 2 ] ] != {} & ] ]; Nest[ f, {1}, 79 ] (* Robert G. Wilson v, Nov 01 2006 *)
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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