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A335884
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The length of a longest path from n to a power of 2, when applying the nondeterministic maps k -> k - k/p and k -> k + k/p, where p can be any of the odd prime factors of k, and the maps can be applied in any order.
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11
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0, 0, 1, 0, 2, 1, 2, 0, 2, 2, 3, 1, 3, 2, 3, 0, 3, 2, 3, 2, 3, 3, 4, 1, 4, 3, 3, 2, 4, 3, 4, 0, 4, 3, 4, 2, 4, 3, 4, 2, 4, 3, 4, 3, 4, 4, 5, 1, 4, 4, 4, 3, 4, 3, 5, 2, 4, 4, 5, 3, 5, 4, 4, 0, 5, 4, 5, 3, 5, 4, 5, 2, 5, 4, 5, 3, 5, 4, 5, 2, 4, 4, 5, 3, 5, 4, 5, 3, 5, 4, 5, 4, 5, 5, 5, 1, 5, 4, 5, 4, 5, 4, 5, 3, 5
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OFFSET
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1,5
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COMMENTS
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The length of a longest path from n to a power of 2, when using the transitions x -> A171462(x) and x -> A335876(x).
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LINKS
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FORMULA
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Fully additive with a(2) = 0, and a(p) = 1+max(a(p-1), a(p+1)), for odd primes p.
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PROG
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(PARI) A335884(n) = { my(f=factor(n)); sum(k=1, #f~, if(2==f[k, 1], 0, f[k, 2]*(1+max(A335884(f[k, 1]-1), A335884(f[k, 1]+1))))); };
(PARI)
\\ Or empirically as:
A171462(n) = if(1==n, 0, (n-(n/vecmax(factor(n)[, 1]))));
A335876(n) = if(1==n, 2, (n+(n/vecmax(factor(n)[, 1]))));
A209229(n) = (n && !bitand(n, n-1));
A335884(n) = if(A209229(n), 0, my(xs=Set([n]), newxs, a, b, u); for(k=1, oo, newxs=Set([]); if(!#xs, return(k-1)); for(i=1, #xs, u = xs[i]; a = A171462(u); if(!A209229(a), newxs = setunion([a], newxs)); b = A335876(u); if(!A209229(b), newxs = setunion([b], newxs))); xs = newxs));
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CROSSREFS
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Cf. A335883 (position of the first occurrence of each n).
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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