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A292253
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a(1) = 0, a(2) = 1, and for n > 2, a(n) = 2*a(A252463(n)) + [n == 1 (mod 2)]*[J(3|n) == 1], where J is the Jacobi-symbol.
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8
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0, 1, 2, 2, 4, 4, 8, 4, 4, 8, 17, 8, 35, 16, 8, 8, 70, 8, 140, 16, 16, 34, 281, 16, 9, 70, 8, 32, 562, 16, 1124, 16, 32, 140, 17, 16, 2249, 280, 68, 32, 4498, 32, 8996, 68, 16, 562, 17993, 32, 19, 18, 140, 140, 35986, 16, 32, 64, 280, 1124, 71973, 32, 143947, 2248, 32, 32, 64, 64, 287894, 280, 560, 34, 575789, 32, 1151579, 4498, 16, 560, 34, 136, 2303158, 64
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OFFSET
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1,3
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COMMENTS
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Base-2 expansion of a(n) encodes the steps where numbers that are either of the form 12k+1 or of the form 12k+11 are encountered when map x -> A252463(x) is iterated down to 1, starting from x=n. An exception is the most significant bit of a(n) which corresponds with the final 1, but is shifted one bit-position towards right.
The AND - XOR formula(s) just restate the fact that J(3|n) = J(-1|n)*J(-3|n), as the Jacobi-symbol is multiplicative (also) with respect to its upper argument.
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LINKS
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FORMULA
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a(1) = 0, a(2) = 1, and for n > 2, a(n) = 2*a(A252463(n)) + [n == 1 (mod 2)]*[J(3|n) == 1], where J is the Jacobi-symbol, and [ ]'s are Iverson brackets, whose product gives 1 only if n is an odd number for which J(3|n) = +1, and 0 otherwise.
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PROG
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(Scheme) (define (A292253 n) (if (<= n 2) (- n 1) (+ (if (and (odd? n) (= 1 (jacobi-symbol 3 n))) 1 0) (* 2 (A292253 (A252463 n))))))
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CROSSREFS
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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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