A109921 - cp's OEIS frontend

A109921 a(2n) = prime(n). a(2n+1) = sum of composite numbers between prime(n) and prime(n+1). We define a(1) = 1.

n	a(n)
1	1
2	2
3	0
4	3
5	4
6	5
7	6
8	7
9	27
10	11
11	12
12	13
13	45
14	17
15	18
16	19
17	63
18	23
19	130
20	29
21	30
22	31
23	170
24	37
25	117
26	41
27	42
28	43
29	135
30	47
31	250
32	53
33	280
34	59
35	60
36	61
37	320
38	67
39	207
40	71
41	72
42	73
43	380
44	79
45	243
46	83
47	430
48	89
49	651
50	97
51	297
52	101
53	102
54	103
55	315
56	107
57	108
58	109
59	333
60	113
61	1560
62	127
63	387
64	131

[1, 2, 0, 3, 4, 5, 6, 7, 27, 11, 12, 13, 45, 17, 18, 19, 63, 23, 130, 29, 30, 31, 170, 37, 117, 41, 42, 43, 135, 47, 250, 53, 280, 59, 60, 61, 320, 67, 207, 71, 72, 73, 380, 79, 243, 83, 430, 89, 651, 97, 297, 101, 102, 103, 315, 107, 108, 109, 333, 113, 1560, 127, 387, 131]

cp's OEIS Frontend

A109921 a(2n) = prime(n). a(2n+1) = sum of composite numbers between prime(n) and prime(n+1). We define a(1) = 1.

Table of values

List of values