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 A120107 a(n) = Sum_{k=0..floor(n/2)} lcm(1,...,2(n-k)+2)/lcm(1,...,2k+2). 2
 1, 6, 31, 425, 1331, 14084, 182533, 390855, 6192220, 117429752, 136000866, 2700408581, 13835919839, 42477252404, 1171690228133, 72397239805085, 84274330442804, 86644937313210, 2686078920033439, 3119346038772923 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Diagonal sums of number triangle A120101. LINKS Muniru A Asiru, Table of n, a(n) for n = 0..1000 PROG (GAP) List([0..20], n->Sum([0..Int(n/2)], k->Lcm(List([1..2*(n-k)+2], i->i))/Lcm(List([1..2*k+2], i->i)))); # Muniru A Asiru, Mar 03 2019 (PARI) a(n) = sum(k=0, n\2, lcm([1..2*(n-k)+2])/lcm([1..2*k+2])); \\ Michel Marcus, Mar 04 2019 CROSSREFS Cf. A120101. Sequence in context: A318539 A221514 A144576 * A015462 A006115 A144780 Adjacent sequences:  A120104 A120105 A120106 * A120108 A120109 A120110 KEYWORD easy,nonn AUTHOR Paul Barry, Jun 09 2006 STATUS approved

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Last modified February 28 01:15 EST 2020. Contains 332319 sequences. (Running on oeis4.)