A227043 - OEIS

A227043

Numerator of harmonic mean H(n,2), n>= 0.

0, 4, 2, 12, 8, 20, 3, 28, 16, 36, 10, 44, 24, 52, 7, 60, 32, 68, 18, 76, 40, 84, 11, 92, 48, 100, 26, 108, 56, 116, 15, 124, 64, 132, 34, 140, 72, 148, 19, 156, 80, 164, 42, 172, 88, 180, 23, 188, 96, 196, 50, 204, 104, 212, 27, 220, 112, 228, 58, 236, 120

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OFFSET

0,2

COMMENTS

a(n) = numerator(H(n,2)) = numerator(4*n/(n+2)), n>=0, with H(n,2) the harmonic mean of n and 2.

The corresponding denominator is given in A000265(n+2), n>= 0.

a(n+2), n>=0, is the second column (m=2) of the triangle A227041.

LINKS

Table of n, a(n) for n=0..60.

FORMULA

a(n) = numerator(4*n/(n+2)), n >= 0.

a(n) = 4*n/gcd(n+2,4*n) = 4*n/gcd(n+2,8), n >= 0.