A286946 -id:A286946 - cp's OEIS frontend

A287006 a(1) = 1; a(n+1) = Sum_{k=1..n} lcm(a(k),a(n))/a(n).

1, 1, 2, 3, 5, 8, 12, 12, 13, 45, 36, 32, 86, 120, 75, 177, 250, 315, 281, 1194, 726, 925, 2695, 2218, 5776, 6808, 6632, 8383, 28449, 34934, 53325, 69653, 153540, 107261, 371925, 241534, 749726, 870493, 1460599, 2623154, 3576448, 4841995, 9911297, 15119248, 19818816, 20257600, 7481107, 80326829

Offset: 1

Ilya Gutkovskiy, Aug 31 2017

nonn

			a(1) = 1;
a(2) = lcm(a(1),a(1))/a(1) = lcm(1,1)/1 = 1;
a(3) = lcm(a(1),a(2))/a(2) + lcm(a(2),a(2))/a(2) = lcm(1,1)/1 + lcm(1,1)/1 = 2;
a(4) = lcm(a(1),a(3))/a(3) + lcm(a(2),a(3))/a(3) + lcm(a(3),a(3))/a(3) = lcm(1,2)/2 + lcm(1,2)/2 + lcm(2,2)/2 = 3, etc.

Ivan Neretin, Table of n, a(n) for n = 1..1000
Index entries for sequences related to lcm's

Cf. A056147, A057661, A286946.

a[1] = 1; a[n_] := a[n] = Sum[LCM[a[k - 1], a[n - 1]]/a[n - 1], {k, 2, n}]; Table[a[n], {n, 48}]
a[1] = 1; a[n_] := a[n] = Sum[a[k - 1]/GCD[a[k - 1], a[n - 1]], {k, 2, n}]; Table[a[n], {n, 48}]

a(1) = 1; a(n+1) = Sum_{k=1..n} a(k)/gcd(a(k),a(n)).

A292303 a(1) = 1; a(n+1) = Sum_{k=1..n} lcm(a(k),n)/n.

Original entry on oeis.org

1, 1, 2, 4, 4, 12, 9, 33, 50, 78, 99, 173, 264, 658, 570, 1056, 1099, 4113, 2443, 10129, 18866, 23226, 39775, 102665, 171529, 256039, 610467, 815809, 1795028, 3854202, 3044396, 10752800, 5509162, 22665306, 25847226, 66558954, 25219183, 167266731, 264535960, 163511658, 346473322, 1109093102

Offset: 1

Ilya Gutkovskiy, Sep 14 2017

nonn

			a(1) = 1;
a(2) = lcm(a(1),1)/1 = lcm(1,1)/1 = 1;
a(3) = lcm(a(1),2)/2 + lcm(a(2),2)/2 = lcm(1,2)/2 + lcm(1,2)/2 = 2;
a(4) = lcm(a(1),3)/3 + lcm(a(2),3)/3 + lcm(a(3),3)/3 = lcm(1,3)/3 + lcm(1,3)/3 + lcm(2,3)/3 = 4, etc.

Index entries for sequences related to lcm's

Cf. A056147, A057661, A286946, A287006.

a[1] = 1; a[n_] := a[n] = Sum[LCM[a[k - 1], n - 1]/(n - 1), {k, 2, n}]; Table[a[n], {n, 42}]
a[1] = 1; a[n_] := a[n] = Sum[a[k - 1]/GCD[a[k - 1], n - 1], {k, 2, n}]; Table[a[n], {n, 42}]

a(1) = 1; a(n+1) = Sum_{k=1..n} a(k)/gcd(a(k),n).

cp's OEIS Frontend

A287006 a(1) = 1; a(n+1) = Sum_{k=1..n} lcm(a(k),a(n))/a(n).

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