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A089313
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Write n in binary; a(n) = number represented by second block of 1's from the right.
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4
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0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 3, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 3, 3, 3, 0, 7, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 0, 3, 3, 3, 3, 1, 3, 3, 0, 7, 7, 7, 0, 15, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 3, 1, 7, 1, 1, 0, 3, 3, 3, 1, 3, 3, 1, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,14
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FORMULA
| a(n) = 2^A089310(n)-1. - David Wasserman (wasserma(AT)spawar.navy.mil), Sep 09 2005
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EXAMPLE
| 13 = 1101 so a(13) = 3.
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PROG
| (PARI) { a(n) = local(b, l, r, c); b=binary(n); l=length(b); while(l&&b[l]==0, l--); while(l&&b[l]==1, l--); while(l&&b[l]==0, l--); r=0; c=0; while(l&&b[l], r+=2^c; l--; c++); r; } for(i=0, 200, print1(a(i), ", ")) (Klasen)
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CROSSREFS
| Cf. A089309-A089312.
Sequence in context: A035677 A143276 A101941 * A052998 A114516 A027185
Adjacent sequences: A089310 A089311 A089312 * A089314 A089315 A089316
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KEYWORD
| nonn,base
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Dec 22 2003
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EXTENSIONS
| More terms from David Wasserman (wasserma(AT)spawar.navy.mil) and Lambert Klasen (Lambert.Klasen(AT)gmx.net), Sep 09 2005
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