A045895 Period length of pairs (a,b) where a has period 2n-2 and b has period n.

0, 2, 12, 12, 40, 30, 84, 56, 144, 90, 220, 132, 312, 182, 420, 240, 544, 306, 684, 380, 840, 462, 1012, 552, 1200, 650, 1404, 756, 1624, 870, 1860, 992, 2112, 1122, 2380, 1260, 2664, 1406, 2964, 1560

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..5000

Ralf W. Grosse-Kunstleve, Origin of EIS sequences A045895 & A045896. [Wayback Machine copy]

Formula

a(n) = A204557(n) - A204556(n). - Reinhard Zumkeller, Jan 18 2012

From Amiram Eldar, Sep 14 2022: (Start)

a(n) = n*(n-1) for n even.

a(n) = 2*n*(n-1) for n odd.

a(n) = lcm(2*n-2, n).

a(n) = 2*A045896(n-2).

Sum_{n>=2} 1/a(n) = (log(2)+1)/2. (End)

Mathematica

Table[ LCM[ 2*n-2, n ], {n, 40} ]

Prog

(PARI) for(n=1, 50, print1(lcm(2*n-2, n), ", ")) \\ G. C. Greubel, Jun 15 2018
(Magma) [Lcm(2*n-2, n): n in [1..50]]; // G. C. Greubel, Jun 15 2018

Crossrefs

Cf. A045896, A204556, A204557.

Sequence in context: A068515 A088240 A168457 * A251421 A226393 A371375

Adjacent sequences: A045892 A045893 A045894 * A045896 A045897 A045898

Keyword

nonn

Author

Ralf W. Grosse-Kunstleve

Status

approved