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A086536
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Least common multiple of numbers obtained by adding one to the odd divisors of n and subtracting 1 from the even divisors of n.
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0
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2, 2, 4, 6, 6, 20, 8, 42, 20, 18, 12, 660, 14, 104, 48, 210, 18, 340, 20, 342, 88, 84, 24, 106260, 78, 350, 140, 2808, 30, 20880, 32, 6510, 204, 198, 72, 78540, 38, 740, 280, 31122, 42, 234520, 44, 3612, 5520, 360, 48, 4994220, 200, 11466, 468, 17850, 54
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = least common multiple of (Ea-1), (Eb-1), (Ec-1), ..., (Oa+1), (Ob+1), (Oc+1)..., where Ea, Eb, Ec, ... and Oa, Ob, Oc, ... are respectively the even and odd divisors of n.
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EXAMPLE
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a(14) = 104. The divisors of 14 are 1,2,7 and 14 and the corresponding numbers obtained are 2,1,8 and 13 whose least common multiple is 104.
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PROG
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(PARI) a(n) = local(d); d = divisors(n); l = 1; for (i = 1, length(d), if (d[i]%2, d[i]++, d[i]--); l = lcm(l, d[i])); l; \\ David Wasserman, Mar 15 2005
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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