A285004 - cp's OEIS frontend

A285004 Numbers n that enter a cycle of greater length than that for any k < n in the iteration sequence s(0)=n, s(k+1) = s(k) + (-1)^k*d(s(k)), where d(n) is the number of divisors of n (A000005).

n	a(n)
1	3
2	93
3	273
4	684
5	3993
6	58695
7	91355
8	167055
9	441519
10	2337513
11	20225991
12	20625997
13	148789675
14	470944675
15	494359089
16	3252701700
17	3472027000
18	9096968436

[3, 93, 273, 684, 3993, 58695, 91355, 167055, 441519, 2337513, 20225991, 20625997, 148789675, 470944675, 494359089, 3252701700, 3472027000, 9096968436]

cp's OEIS Frontend

A285004 Numbers n that enter a cycle of greater length than that for any k < n in the iteration sequence s(0)=n, s(k+1) = s(k) + (-1)^k*d(s(k)), where d(n) is the number of divisors of n (A000005).

Table of values

List of values