A179921 - cp's OEIS frontend

A179921 a(n) = prime(n) if n<=3; for n>3, a(n) is the smallest prime >a(n-1), such that the denominator of fraction (a(n-1)-a(n-2))/(a(n)-a(n-1)) did not appear earlier.

n	a(n)
1	2
2	3
3	5
4	7
5	13
6	23
7	31
8	53
9	67
10	79
11	113
12	131
13	151
14	193
15	233
16	271
17	307
18	353
19	379
20	409
21	457
22	557
23	613
24	691
25	761
26	809
27	883
28	907
29	1013
30	1069
31	1123
32	1181
33	1213
34	1279
35	1361
36	1423
37	1483
38	1571
39	1657
40	1709
41	1811
42	1933
43	1997
44	2087
45	2179
46	2273
47	2341
48	2459

[2, 3, 5, 7, 13, 23, 31, 53, 67, 79, 113, 131, 151, 193, 233, 271, 307, 353, 379, 409, 457, 557, 613, 691, 761, 809, 883, 907, 1013, 1069, 1123, 1181, 1213, 1279, 1361, 1423, 1483, 1571, 1657, 1709, 1811, 1933, 1997, 2087, 2179, 2273, 2341, 2459]

cp's OEIS Frontend

A179921 a(n) = prime(n) if n<=3; for n>3, a(n) is the smallest prime >a(n-1), such that the denominator of fraction (a(n-1)-a(n-2))/(a(n)-a(n-1)) did not appear earlier.

Table of values

List of values