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A089263
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First differences of A023416.
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0
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0, 0, 1, -1, 2, -1, 0, -1, 3, -1, 0, -1, 1, -1, 0, -1, 4, -1, 0, -1, 1, -1, 0, -1, 2, -1, 0, -1, 1, -1, 0, -1, 5, -1, 0, -1, 1, -1, 0, -1, 2, -1, 0, -1, 1, -1, 0, -1, 3, -1, 0, -1, 1, -1, 0, -1, 2, -1, 0, -1, 1, -1, 0, -1, 6, -1, 0, -1, 1, -1, 0, -1, 2, -1, 0, -1, 1, -1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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FORMULA
| a(0)=0, a(2n) = a(n) + 1, a(2n+1) = -1 + [n==0].
a(n) = A007814(n) + A036987(n-1) - 1.
G.f.: sum(k>=0, t^2/(1+t), t=x^2^k).
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PROG
| (PARI) a(n)=valuation(n, 2)+(2^valuation(n, 2)==n)-1
(PARI) a(n)=if(n<1, 0, if(n%2==0, a(n/2)+1, -1+(((n-1)/2)==0)))
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CROSSREFS
| Cf. A088705.
Sequence in context: A052249 A030528 A077227 * A156135 A047265 A185962
Adjacent sequences: A089260 A089261 A089262 * A089264 A089265 A089266
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KEYWORD
| sign,easy
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AUTHOR
| Ralf Stephan (ralf(AT)ark.in-berlin.de), Oct 30 2003
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