A002375
From Goldbach conjecture: number of decompositions of 2n into an unordered sum of two odd primes.
0, 0, 1, 1, 2, 1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 2, 4, 4, 2, 3, 4, 3, 4, 5, 4, 3, 5, 3, 4, 6, 3, 5, 6, 2, 5, 6, 5, 5, 7, 4, 5, 8, 5, 4, 9, 4, 5, 7, 3, 6, 8, 5, 6, 8, 6, 7, 10, 6, 6, 12, 4, 5, 10, 3, 7, 9, 6, 5, 8, 7, 8, 11, 6, 5, 12, 4, 8, 11, 5, 8, 10, 5, 6, 13, 9, 6, 11, 7, 7, 14, 6, 8, 13, 5, 8, 11, 7, 9……
序数 素数对
1 0
2 0
3 1
4 1
5 2
6 1
7 2
8 2
9 2
10 2
11 3
12 3
13 3
14 2
15 3
16 2
17 4
18 4
19 2
20 3
21 4
22 3
23 4
24 5
25 4
26 3
27 5
28 3
29 4
30 6
……
769 26
770 46
771 46
772 21
……
19999 323
20000 389
序数乘以2就是偶数。 |