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A332929
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Position where the binary expansion of n occurs for the first time in the binary expansion of Pi.
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1
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3, 1, 2, 1, 2, 18, 1, 13, 8, 2, 21, 18, 1, 17, 16, 13, 8, 27, 2, 62, 25, 21, 18, 93, 49, 1, 20, 17, 95, 16, 15, 13, 97, 8, 27, 45, 2, 128, 62, 146, 25, 60, 21, 395, 229, 18, 93, 209, 49, 65, 1, 78, 42, 20, 17, 105, 95, 116, 186, 16, 175, 15, 14, 13, 97, 110
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OFFSET
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0,1
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LINKS
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EXAMPLE
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In binary, Pi = 11.00100100.... The bitstring 10 (for 2) occurs at position 2, so a(2) = 2.
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MATHEMATICA
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p = RealDigits[Pi, 2, 500][[1]]; L = {}; Do[t = SequencePosition[p, IntegerDigits[n, 2], 1]; If[t == {}, Break[], AppendTo[L, t[[1, 1]]]], {n, 0, 65}]; L (* Giovanni Resta, Mar 16 2020 *)
Module[{nn=500, bp}, bp=RealDigits[Pi, 2, nn][[1]]; Table[ SequencePosition[ bp, IntegerDigits[n, 2], 1][[All, 1]], {n, 0, 70}]]//Flatten (* Harvey P. Dale, Sep 18 2021 *)
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PROG
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(Perl)
#! /usr/bin/perl
# Feed b004601.txt to this to get the binary digits of Pi.
while (<>) {
chomp;
(undef, $d[$n++]) = split(" ");
}
$pi = join("", @d);
$k = 0;
while (1) {
last if ($pos = index($pi, sprintf("%b", $k++))) < 0;
$out .= $pos +2 . ", ";
}
print $out, "\n";
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CROSSREFS
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Cf. A032445 (for decimal expansion rather than binary).
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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