A308344 - cp's OEIS frontend

A308344 a(n) = (A001359(n+1)^2 - 1)/24, where A001359 = lesser of twin primes; or: pentagonal numbers (A000326) whose indices are twin ranks (A002822).

n	a(n)
1	1
2	5
3	12
4	35
5	70
6	145
7	210
8	425
9	477
10	782
11	925
12	1335
13	1520
14	1617
15	2147
16	2380
17	3015
18	3290
19	4030
20	5017
21	7315
22	7740
23	8855
24	11310
25	13490
26	14950
27	15862
28	17120
29	18095
30	27270
31	28085
32	28497
33	30602
34	32340
35	43265
36	44290
37	45850
38	46905
39	49595
40	55200
41	62935
42	67947
43	69230
44	70525

[1, 5, 12, 35, 70, 145, 210, 425, 477, 782, 925, 1335, 1520, 1617, 2147, 2380, 3015, 3290, 4030, 5017, 7315, 7740, 8855, 11310, 13490, 14950, 15862, 17120, 18095, 27270, 28085, 28497, 30602, 32340, 43265, 44290, 45850, 46905, 49595, 55200, 62935, 67947, 69230, 70525]

cp's OEIS Frontend

A308344 a(n) = (A001359(n+1)^2 - 1)/24, where A001359 = lesser of twin primes; or: pentagonal numbers (A000326) whose indices are twin ranks (A002822).

Table of values

List of values