A086536 - OEIS

A086536

Least common multiple of numbers obtained by adding one to the odd divisors of n and subtracting 1 from the even divisors of n.

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

1,1

LINKS

Table of n, a(n) for n=1..53.

FORMULA

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.

EXAMPLE

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.

PROG

(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

CROSSREFS

Cf. A086535.

Sequence in context: A102425 A162608 A143216 * A053045 A152424 A145804

Adjacent sequences: A086533 A086534 A086535 * A086537 A086538 A086539

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Aug 18 2003

EXTENSIONS

More terms from David Wasserman, Mar 15 2005

STATUS

approved