A066784 - cp's OEIS frontend

A066784 Numbers n such that (n, sigma(n)) lies on the hyperbola y^2 - x^2 = m^2, for some natural number m, i.e., sigma(n)^2 - n^2 = m^2.

n	a(n)
1	1
2	90
3	392448
4	411264
5	804384
6	871416
7	1284192
8	1935360
9	7456512
10	396168192
11	24193572480
12	43171285248
13	54585498240
14	63178786944
15	123570274464
16	730078562304
17	823442861592
18	1420069242240
19	2354025332736
20	2506251331584
21	3606011136000
22	3697798293504
23	9951618862080

[1, 90, 392448, 411264, 804384, 871416, 1284192, 1935360, 7456512, 396168192, 24193572480, 43171285248, 54585498240, 63178786944, 123570274464, 730078562304, 823442861592, 1420069242240, 2354025332736, 2506251331584, 3606011136000, 3697798293504, 9951618862080]

cp's OEIS Frontend

A066784 Numbers n such that (n, sigma(n)) lies on the hyperbola y^2 - x^2 = m^2, for some natural number m, i.e., sigma(n)^2 - n^2 = m^2.

Table of values

List of values