A057773 - cp's OEIS frontend

A057773 a(n) = Sum_{i=1..n} nu_2(prime(i) - 1) where nu_2(m) = exponent of highest power of 2 dividing m.

n	a(n)
1	0
2	1
3	3
4	4
5	5
6	7
7	11
8	12
9	13
10	15
11	16
12	18
13	21
14	22
15	23
16	25
17	26
18	28
19	29
20	30
21	33
22	34
23	35
24	38
25	43
26	45
27	46
28	47
29	49
30	53
31	54
32	55
33	58
34	59
35	61
36	62
37	64
38	65
39	66
40	68
41	69
42	71
43	72
44	78
45	80
46	81
47	82
48	83
49	84
50	86
51	89
52	90
53	94
54	95
55	103
56	104
57	106
58	107
59	109
60	112
61	113
62	115
63	116
64	117
65	120
66	122
67	123

[0, 1, 3, 4, 5, 7, 11, 12, 13, 15, 16, 18, 21, 22, 23, 25, 26, 28, 29, 30, 33, 34, 35, 38, 43, 45, 46, 47, 49, 53, 54, 55, 58, 59, 61, 62, 64, 65, 66, 68, 69, 71, 72, 78, 80, 81, 82, 83, 84, 86, 89, 90, 94, 95, 103, 104, 106, 107, 109, 112, 113, 115, 116, 117, 120, 122, 123]

cp's OEIS Frontend

A057773 a(n) = Sum_{i=1..n} nu_2(prime(i) - 1) where nu_2(m) = exponent of highest power of 2 dividing m.

Table of values

List of values

n	a(n)
1	0
2	1
3	3
4	4
5	5
6	7
7	11
8	12
9	13
10	15
11	16
12	18
13	21
14	22
15	23
16	25
17	26
18	28
19	29
20	30
21	33
22	34
23	35
24	38
25	43
26	45
27	46
28	47
29	49
30	53
31	54
32	55
33	58
34	59
35	61
36	62
37	64
38	65
39	66
40	68
41	69
42	71
43	72
44	78
45	80
46	81
47	82
48	83
49	84
50	86
51	89
52	90
53	94
54	95
55	103
56	104
57	106
58	107
59	109
60	112
61	113
62	115
63	116
64	117
65	120
66	122
67	123

n	a(n)
1	0
2	1
3	3
4	4
5	5
6	7
7	11
8	12
9	13
10	15
11	16
12	18
13	21
14	22
15	23
16	25
17	26
18	28
19	29
20	30
21	33
22	34
23	35
24	38
25	43
26	45
27	46
28	47
29	49
30	53
31	54
32	55
33	58
34	59
35	61
36	62
37	64
38	65
39	66
40	68
41	69
42	71
43	72
44	78
45	80
46	81
47	82
48	83
49	84
50	86
51	89
52	90
53	94
54	95
55	103
56	104
57	106
58	107
59	109
60	112
61	113
62	115
63	116
64	117
65	120
66	122
67	123

n	a(n)
1	0
2	1
3	3
4	4
5	5
6	7
7	11
8	12
9	13
10	15
11	16
12	18
13	21
14	22
15	23
16	25
17	26
18	28
19	29
20	30
21	33
22	34
23	35
24	38
25	43
26	45
27	46
28	47
29	49
30	53
31	54
32	55
33	58
34	59
35	61
36	62
37	64
38	65
39	66
40	68
41	69
42	71
43	72
44	78
45	80
46	81
47	82
48	83
49	84
50	86
51	89
52	90
53	94
54	95
55	103
56	104
57	106
58	107
59	109
60	112
61	113
62	115
63	116
64	117
65	120
66	122
67	123