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A362937
a(n) = (A000982(n) - A362931(n))/2.
2
0, 0, 1, 2, 4, 4, 7, 10, 14, 18, 23, 26, 32, 38, 43, 50, 58, 64, 73, 80, 90, 100, 111, 120, 132, 144, 157, 168, 182, 192, 207, 222, 238, 254, 269, 284, 302, 320, 339, 356, 376, 392, 413, 434, 452, 474, 497, 518, 542, 566, 591, 616, 642, 666, 693, 718, 746, 774, 803, 826, 856, 886, 915, 946, 978
OFFSET
1,4
COMMENTS
a(n) = one-half of (number of pairs (i,j) in [1..n] X [1..n] with integral arithmetic mean) - (number of pairs (i,j) in [1..n] X [1..n] with integral harmonic mean).
LINKS
PROG
(Python)
def A362937(n): return ((n-1)**2>>2)-sum(1 for x in range(1, n+1) for y in range(1, x) if not (x*y<<1)%(x+y)) # Chai Wah Wu, Aug 29 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Aug 28 2023
STATUS
approved