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Search: id:A133468
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| A133468 |
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A080814 complemented, then interpreted as binary and then re-expressed in decimal form (e.g. "1221" = "0110"). Alternately, view as A080814 with "1" mapped to "1" and "2" mapped to "0". |
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+0
2
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| 1, 2, 9, 150, 38505, 2523490710, 10838310072981296745
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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The "~" operator, as used here, represents binary inversion/complement. a(0) = 1 a(n) = a(n-1) followed by ~a(n-1)
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PROGRAM
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function invert(string s) returns string { s.replace("0", "2"); s.replace("1", "0"); s.replace("2", "1"); } function f(int n) returns string { if (n==0) return "1"; return concat(f(n-1), invert(f(n-1)); //Blatant opportunity for optimization } function a(int n) returns int { return f(n).InterpretAsBinary(); }
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CROSSREFS
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Cf. A080814, A080815, A048707.
Sequence in context: A110860 A050995 A117116 this_sequence A081459 A038843 A053294
Adjacent sequences: A133465 A133466 A133467 this_sequence A133469 A133470 A133471
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KEYWORD
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nonn
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AUTHOR
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Dan Reif (integer-sequences(AT)angelfaq.com), Nov 28 2007, corrected Nov 30 2007
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