login
A227107
Numerators of harmonic mean H(n,4), n >= 0.
2
0, 8, 8, 24, 4, 40, 24, 56, 16, 72, 40, 88, 6, 104, 56, 120, 32, 136, 72, 152, 20, 168, 88, 184, 48, 200, 104, 216, 7, 232, 120, 248, 64, 264, 136, 280, 36, 296, 152, 312, 80, 328, 168, 344, 22, 360, 184, 376, 96, 392, 200, 408, 52, 424, 216
OFFSET
0,2
COMMENTS
a(n) = numerator(H(n,4)) = numerator(8*n/(n+4)), n>=0, with H(n,4) the harmonic mean of n and 4.
The corresponding denominators are given in A000265(n+4), n >= 0.
a(n+4), n>=0, is the fourth column (m=4) of the triangle A227041.
FORMULA
a(n) = numerator(8*n/(n+4)), n >= 0.
a(n) = 8*n/gcd(n+4,8*n) = 8*n/gcd(n+4,32), n >= 0.
EXAMPLE
The rationals H(n,4) begin: 0, 8/5, 8/3, 24/7, 4, 40/9, 24/5, 56/11, 16/3, 72/13, 40/7, 88/15, 6, 104/17, 56/9, 120/19, ...
CROSSREFS
Cf. A227041(n+4,4), A227140(n+8) (denominators), n >= 0.
Sequence in context: A061156 A359037 A195862 * A205382 A109049 A160239
KEYWORD
nonn,frac,easy
AUTHOR
Wolfdieter Lang, Jul 01 2013
STATUS
approved