A101993 - cp's OEIS frontend

A101993 Indices k for which the numerator of Sum_{i=2..k} ( (-1)^i/(i * phi(i)) ) is a prime number.

n	a(n)
1	4
2	6
3	7
4	9
5	10
6	13
7	16
8	21
9	27
10	35
11	39
12	41
13	45
14	48
15	52
16	76
17	84
18	94
19	119
20	150
21	165
22	190
23	251
24	260
25	264
26	306
27	416
28	428
29	488
30	513
31	521
32	523
33	553
34	615
35	622
36	640
37	711
38	714
39	765
40	797
41	807
42	888
43	967
44	1146
45	1292
46	1555
47	1602
48	1750
49	1822
50	1859
51	1868
52	1950
53	2009
54	2059

[4, 6, 7, 9, 10, 13, 16, 21, 27, 35, 39, 41, 45, 48, 52, 76, 84, 94, 119, 150, 165, 190, 251, 260, 264, 306, 416, 428, 488, 513, 521, 523, 553, 615, 622, 640, 711, 714, 765, 797, 807, 888, 967, 1146, 1292, 1555, 1602, 1750, 1822, 1859, 1868, 1950, 2009, 2059]

cp's OEIS Frontend

A101993 Indices k for which the numerator of Sum_{i=2..k} ( (-1)^i/(i * phi(i)) ) is a prime number.

Table of values

List of values