A081973 - cp's OEIS frontend

A081973 a(1) = 1; a(n) = a(n-1) + sigma(a(n-1)) where sigma(k) = sum of the divisors of k.

n	a(n)
1	1
2	2
3	5
4	11
5	23
6	47
7	95
8	215
9	479
10	959
11	2063
12	4127
13	8255
14	19007
15	38327
16	76655
17	168647
18	338663
19	708263
20	1453823
21	3308543
22	7154303
23	14919599
24	29910119
25	59820239
26	119676959
27	239387375
28	538142975
29	1205440295
30	2651968655
31	6663140495

[1, 2, 5, 11, 23, 47, 95, 215, 479, 959, 2063, 4127, 8255, 19007, 38327, 76655, 168647, 338663, 708263, 1453823, 3308543, 7154303, 14919599, 29910119, 59820239, 119676959, 239387375, 538142975, 1205440295, 2651968655, 6663140495]

cp's OEIS Frontend

A081973 a(1) = 1; a(n) = a(n-1) + sigma(a(n-1)) where sigma(k) = sum of the divisors of k.

Table of values

List of values