A057564 - cp's OEIS frontend

A057564 Natural numbers n for which the following three properties hold: (i) Phi[Sigma[n]]=2phi(n), (ii) Sigma[n-2]=2Sigma[Phi[n-2]], (iii) Sigma[n+2]=2*Sigma[Phi[n+2]].

n	a(n)
1	666
2	19674
3	309114
4	369594
5	715194
6	1180026
7	1924794
8	2722266
9	2741274
10	4261914
11	5564826
12	6296634
13	6623226
14	6826266
15	7206906
16	9726648
17	15956154
18	16046874
19	16478874
20	19263546
21	25333146
22	27706554
23	28151514
24	32938074

[666, 19674, 309114, 369594, 715194, 1180026, 1924794, 2722266, 2741274, 4261914, 5564826, 6296634, 6623226, 6826266, 7206906, 9726648, 15956154, 16046874, 16478874, 19263546, 25333146, 27706554, 28151514, 32938074]

cp's OEIS Frontend

A057564 Natural numbers n for which the following three properties hold: (i) Phi[Sigma[n]]=2phi(n), (ii) Sigma[n-2]=2Sigma[Phi[n-2]], (iii) Sigma[n+2]=2*Sigma[Phi[n+2]].

Table of values

List of values

cp's OEIS Frontend

A057564 Natural numbers n for which the following three properties hold: (i) Phi[Sigma[n]]=2*phi(n), (ii) Sigma[n-2]=2*Sigma[Phi[n-2]], (iii) Sigma[n+2]=2*Sigma[Phi[n+2]].

Table of values

List of values

A057564 Natural numbers n for which the following three properties hold: (i) Phi[Sigma[n]]=2phi(n), (ii) Sigma[n-2]=2Sigma[Phi[n-2]], (iii) Sigma[n+2]=2*Sigma[Phi[n+2]].