A139422 - cp's OEIS frontend

A139422 a(1)=a(2)=1. For n >= 3, a(n) = a(n-1) + d(a(n-1)) + d(a(n-2)), where d(m) is the number of positive divisors of m.

n	a(n)
1	1
2	1
3	3
4	6
5	12
6	22
7	32
8	42
9	56
10	72
11	92
12	110
13	124
14	138
15	152
16	168
17	192
18	222
19	244
20	258
21	272
22	290
23	308
24	328
25	348
26	368
27	390
28	416
29	444
30	468
31	498
32	524
33	538
34	548
35	558
36	576
37	609
38	638
39	654
40	670
41	686
42	702
43	726
44	754
45	774
46	794
47	810
48	834
49	862
50	874

[1, 1, 3, 6, 12, 22, 32, 42, 56, 72, 92, 110, 124, 138, 152, 168, 192, 222, 244, 258, 272, 290, 308, 328, 348, 368, 390, 416, 444, 468, 498, 524, 538, 548, 558, 576, 609, 638, 654, 670, 686, 702, 726, 754, 774, 794, 810, 834, 862, 874]

cp's OEIS Frontend

A139422 a(1)=a(2)=1. For n >= 3, a(n) = a(n-1) + d(a(n-1)) + d(a(n-2)), where d(m) is the number of positive divisors of m.

Table of values

List of values

n	a(n)
1	1
2	1
3	3
4	6
5	12
6	22
7	32
8	42
9	56
10	72
11	92
12	110
13	124
14	138
15	152
16	168
17	192
18	222
19	244
20	258
21	272
22	290
23	308
24	328
25	348
26	368
27	390
28	416
29	444
30	468
31	498
32	524
33	538
34	548
35	558
36	576
37	609
38	638
39	654
40	670
41	686
42	702
43	726
44	754
45	774
46	794
47	810
48	834
49	862
50	874

n	a(n)
1	1
2	1
3	3
4	6
5	12
6	22
7	32
8	42
9	56
10	72
11	92
12	110
13	124
14	138
15	152
16	168
17	192
18	222
19	244
20	258
21	272
22	290
23	308
24	328
25	348
26	368
27	390
28	416
29	444
30	468
31	498
32	524
33	538
34	548
35	558
36	576
37	609
38	638
39	654
40	670
41	686
42	702
43	726
44	754
45	774
46	794
47	810
48	834
49	862
50	874

n	a(n)
1	1
2	1
3	3
4	6
5	12
6	22
7	32
8	42
9	56
10	72
11	92
12	110
13	124
14	138
15	152
16	168
17	192
18	222
19	244
20	258
21	272
22	290
23	308
24	328
25	348
26	368
27	390
28	416
29	444
30	468
31	498
32	524
33	538
34	548
35	558
36	576
37	609
38	638
39	654
40	670
41	686
42	702
43	726
44	754
45	774
46	794
47	810
48	834
49	862
50	874