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A059906
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Index of second half of decomposition of integers into pairs based on A000695.
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15
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0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 2, 2, 3, 3, 0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 2, 2, 3, 3, 4, 4, 5, 5, 4, 4, 5, 5, 6, 6, 7, 7, 6, 6, 7, 7, 4, 4, 5, 5, 4, 4, 5, 5, 6, 6, 7, 7, 6, 6, 7, 7, 0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 2, 2, 3, 3, 0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 2, 2, 3, 3, 4, 4, 5, 5, 4, 4, 5, 5, 6
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,9
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COMMENTS
| One coordinate of a recursive non-self intersecting walk on the square lattice Z^2.
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FORMULA
| n = A000695(A059905(n))+2*A000695(a(n))
To get a(n), write n as Sum b_j*2^j, then a(n)=Sum b_(2j+1)*2^j. [From Vladimir Shevelev (shevelev(AT)bgu.ac.il), Nov 13 2008]
a(n)=Sum_k>=0 {A030308(n,k)*b(k)} with b(0)=0 and b(k)=A077957(k-1) for k>0.- From DELEHAM Philippe, Oct 18 2011.
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EXAMPLE
| A000695(A059905(14))+2*A000695(a(14)) = A000695(2)+2*A000695(3) = 4+2*5 = 14.
If n=27, then b_0=1, b_1=1, b_2=0, b_3=1, b_4=1. Therefore a(n)=b_1+b_3*2=3. [From Vladimir Shevelev (shevelev(AT)bgu.ac.il), Nov 13 2008]
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CROSSREFS
| Cf. A000695, A059905.
Sequence in context: A071820 A055092 A130326 * A112046 A076902 A049113
Adjacent sequences: A059903 A059904 A059905 * A059907 A059908 A059909
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KEYWORD
| easy,nonn
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AUTHOR
| Marc LeBrun (mlb(AT)well.com), Feb 07 2001
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