A056136 Largest positive integer whose harmonic mean with another positive integer is n.

1, 2, 6, 6, 15, 12, 28, 20, 45, 30, 66, 42, 91, 56, 120, 72, 153, 90, 190, 110, 231, 132, 276, 156, 325, 182, 378, 210, 435, 240, 496, 272, 561, 306, 630, 342, 703, 380, 780, 420, 861, 462, 946, 506, 1035, 552, 1128, 600, 1225, 650, 1326, 702, 1431, 756, 1540

Offset: 1

Author

Henry Bottomley, Jun 13 2000

Keywords

• nonn

Crossrefs

Cf. A008619 for the smallest integer whose harmonic mean with another integer is n (i.e. harmonic mean of A008619 and a(n) is n).

Formula

a(n) =1/(2/n-1/floor[n/2+1]) =n*A008619(n)/(2*A008619(n)-n) =(n/2)*A029578(n+2)