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A275470
Half the difference between the larger and smaller terms of the n-th amicable pair (x,y) given in A259933.
3
32, 13, 152, 272, 68, 56, 1155, 560, 32, 2025, 6532, 9009, 4490, 11835, 392, 8775, 5756, 13210, 2240, 2288, 9032, 2860, 42272, 40652, 55426, 21592, 8944, 8575, 5840, 1755, 34648, 38072, 4664, 33536, 38296, 57796, 35296, 30555, 10856, 41384
OFFSET
1,1
COMMENTS
Each term represents the radius of an interval (x,y), where x (A260086) and y (A260087) form a pair of amicable numbers (A259933). The midpoint and length of each interval can be found in A275316 and A275469, respectively.
A term will be odd if and only if y-x = 2 mod 4. This occurs when x and y have the same parity but their average has the opposite parity.
This sequence is a rearrangement of A162884 (which is based on A002025, A002046, and A066539). The first ten indices for which a(n) does not equal A162884(n) are n = 9, 10, 11, 15, 16, 33, 34, 35, 41, 42.
LINKS
FORMULA
a(n) = [A260087(n) - A260086(n)]/2 = A275469(n)/2.
EXAMPLE
a(1) = (284-220)/2 = 64/2 = 32, a(2) = (1210-1184)/2 = 26/2 = 13, and a(3) = (2924-2620)/2 = 304/2 = 152.
KEYWORD
nonn
AUTHOR
Timothy L. Tiffin, Jul 28 2016
STATUS
approved