A277187 Numbers n such that A001158(n) == 1 (mod n).

2, 3, 4, 5, 7, 8, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 36, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 121, 125, 127, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 289, 293

Offset

1,1

Comments

Essentially the same as A087797. - Ilya Gutkovskiy, Dec 26 2016

Links

Table of n, a(n) for n=1..73.

Example

a(1) = 2 because sigma_3(2) = 1^3 + 2^3 = 9 and 9 == 1 (mod 2);
a(2) = 3 because sigma_3(3) = 1^3 + 3^3 = 28 and 28 == 1 (mod 3);
a(3) = 4 because sigma_3(4) = 1^3 + 2^3 + 4^3 = 73 and 73 == 1 (mod 4), etc.

Mathematica

Select[Range[300], Mod[DivisorSigma[3, #1], #1] == 1 & ]

Crossrefs

Cf. A000040, A000430, A001158, A001248, A030078, A087797.

Sequence in context: A283262 A334393 A115975 * A339841 A087797 A340815

Adjacent sequences: A277184 A277185 A277186 * A277188 A277189 A277190

Keyword

nonn,easy

Author

Ilya Gutkovskiy, Oct 04 2016

Extensions

Edited by Ilya Gutkovskiy, Dec 26 2016

Status

approved