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A120109 Row sums of number triangle A120108. 2
1, 3, 10, 21, 106, 107, 750, 1501, 4504, 4505, 49556, 49557, 644242, 644243, 644244, 1288489, 21904314, 21904315, 416181986, 416181987, 416181988, 416181989, 9572185748, 9572185749, 47860928746, 47860928747, 143582786242 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

It appears that the indices k such that a(k) = a(k-1) + 1 are A080765. - Michel Marcus, Mar 04 2019

LINKS

Muniru A Asiru, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = Sum_{k=0..n} lcm(1,...,n+1)/lcm(1,...,k+1).

PROG

(GAP) List([0..30], n->Sum([0..n], k->Lcm(List([1..n+1], i->i))/Lcm(List([1..k+1], i->i)))); # Muniru A Asiru, Mar 03 2019

(PARI) a(n) = lcm([1..n+1])*sum(k=0, n, 1/lcm([1..k+1])); \\ Michel Marcus, Mar 04 2019

CROSSREFS

Cf. A080765, A120108.

Sequence in context: A207646 A071563 A139116 * A286067 A158030 A068082

Adjacent sequences:  A120106 A120107 A120108 * A120110 A120111 A120112

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Jun 09 2006

STATUS

approved

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Last modified February 21 02:02 EST 2020. Contains 332086 sequences. (Running on oeis4.)