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A255309
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Number of times log_2 can be applied to n until the result is either 1 or not a power of 2. Here log_2 means the base-2 logarithm.
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3
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0, 0, 1, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
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OFFSET
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0,5
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LINKS
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FORMULA
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a(n) = 1 + a(log_2(n)) if n is a power of 2 except 1, 0 otherwise.
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PROG
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(PARI) nbi(n) = {my(nb = 0); if ((ispower(n, , &m) && (m==2)) || (n==2), return(nbi(valuation(n, 2))+1); ); nb; }
a(n) = { my(nb = 0); if ((ispower(n, , &m) && (m==2)) || (n==2), return(nbi(valuation(n, 2))+1); ); nb; } \\ Michel Marcus, Mar 11 2015; corrected Jun 13 2022
(PARI) A255309(n) = { my(k=0); while((n>1)&&!bitand(n, n-1), n = valuation(n, 2); k++); (k); }; \\ Antti Karttunen, Sep 30 2018
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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