A081478 - cp's OEIS frontend

A081478 Consider the mapping f(a/b) = (a - b)/(ab). Taking a = 2 and b = 1 to start with and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 2/1,1/2,-1/2,-3/-2,-1/6,... Sequence contains the denominators.

n	a(n)
1	1
2	2
3	2
4	-2
5	6
6	-6
7	42
8	-42
9	1806
10	-1806
11	3263442
12	-3263442
13	10650056950806
14	-10650056950806
15	113423713055421844361000442
16	-113423713055421844361000442
17	12864938683278671740537145998360961546653259485195806

[1, 2, 2, -2, 6, -6, 42, -42, 1806, -1806, 3263442, -3263442, 10650056950806, -10650056950806, 113423713055421844361000442, -113423713055421844361000442, 12864938683278671740537145998360961546653259485195806]

cp's OEIS Frontend

A081478 Consider the mapping f(a/b) = (a - b)/(ab). Taking a = 2 and b = 1 to start with and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 2/1,1/2,-1/2,-3/-2,-1/6,... Sequence contains the denominators.

Table of values

List of values