A172438 - cp's OEIS frontend

A172438 Numbers k such that tau(k^2+1) - tau(k^2) = 1 where the function tau(k) is the number of positive divisors of k.

n	a(n)
1	1
2	3
3	5
4	11
5	19
6	27
7	29
8	59
9	61
10	71
11	79
12	101
13	125
14	131
15	139
16	181
17	199
18	242
19	243
20	271
21	333
22	349
23	379
24	387
25	409
26	423
27	449
28	461
29	477
30	521
31	569
32	571
33	603
34	631
35	641
36	661
37	739
38	747
39	751
40	772
41	788
42	821
43	881
44	929
45	991
46	1017
47	1031
48	1039
49	1051
50	1058
51	1069
52	1075
53	1083

[1, 3, 5, 11, 19, 27, 29, 59, 61, 71, 79, 101, 125, 131, 139, 181, 199, 242, 243, 271, 333, 349, 379, 387, 409, 423, 449, 461, 477, 521, 569, 571, 603, 631, 641, 661, 739, 747, 751, 772, 788, 821, 881, 929, 991, 1017, 1031, 1039, 1051, 1058, 1069, 1075, 1083]

cp's OEIS Frontend

A172438 Numbers k such that tau(k^2+1) - tau(k^2) = 1 where the function tau(k) is the number of positive divisors of k.

Table of values

List of values