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 A120110 Diagonal sums of number triangle A120108. 2
 1, 2, 7, 15, 67, 92, 461, 1065, 3016, 3956, 29478, 42231, 379107, 547556, 603421, 991923, 12709228, 18540622, 241033695, 352271227, 389226278, 407797820, 5532937710, 8097345425, 30368363481, 41503874738, 98701094676, 127342427241 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Muniru A Asiru, Table of n, a(n) for n = 0..1000 FORMULA a(n) = Sum_{k=0..floor(n/2)} lcm(1,..,n-k+1)/lcm(1,..,k+1). PROG (GAP) List([0..30], n->Sum([0..Int(n/2)], k->Lcm(List([1..n-k+1], i->i))/Lcm(List([1..k+1], i->i)))); # Muniru A Asiru, Mar 04 2019 (PARI) a(n) = sum(k=0, n\2, lcm([1..n-k+1])/lcm([1..k+1])); \\ Michel Marcus, Mar 04 2019 CROSSREFS Cf. A120108. Sequence in context: A279286 A282197 A050612 * A047694 A262016 A129666 Adjacent sequences:  A120107 A120108 A120109 * A120111 A120112 A120113 KEYWORD easy,nonn AUTHOR Paul Barry, Jun 09 2006 STATUS approved

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Last modified January 17 12:45 EST 2020. Contains 330958 sequences. (Running on oeis4.)