A001031
Goldbach conjecture: a(n) = number of decompositions of 2n into sum of two primes (counting 1 as a prime).
1, 2, 2, 2, 2, 2, 3, 2, 3, 3, 3, 4, 3, 2, 4, 3, 4, 4, 3, 3, 5, 4, 4, 6, 4, 3, 6, 3, 4, 7, 4, 5, 6, 3, 5, 7, 6, 5, 7, 5, 5, 9, 5, 4, 10, 4, 5, 7, 4, 6, 9, 6, 6, 9, 7, 7, 11, 6, 6, 12, 4, 5, 10, 4, 7, 10, 6, 5, 9, 8, 8, 11, 6, 5, 13, 5, 8, 11, 6, 8, 10, 6, 6, 14, 9, 6, 12, 7, 7, 15, 7, 8, 13, 5, 8, 12, 8, 9……
1 1——2=1+1
2 2——4=2+2
3 2——6=1+5=3+3
4 2
5 2
6 2
7 3
8 2
9 3
10 3
11 3
12 4
13 3
14 2
15 4
16 3
17 4
18 4
19 3——38=1+37=7+31=19+19
20 3——40=3+37=11+29=17+23
21 5
22 4
23 4
24 6
25 4
26 3
27 6
28 3
29 4
30 7
31 4
32 5
33 6
34 3
35 5
36 7
37 6
38 5
39 7
40 5
41 5
42 9
43 5
44 4
45 10
46 4
47 5
48 7
49 4
50 6
51 9
52 6
53 6
54 9
55 7
56 7
57 11
58 6
59 6
60 12
61 4
62 5
63 10
64 4
65 7
66 10
67 6
68 5
69 9
70 8
71 8
72 11
73 6
74 5
75 13
76 5
77 8
78 11
79 6
80 8
81 10
82 6
83 6
84 14
85 9
86 6
87 12
88 7
89 7
90 15
91 7
92 8
93 13
94 5
95 8
96 12
97 8
98 9
99 14
100 9
……
10000 231 |