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A277187 Numbers n such that A001158(n) == 1 (mod n). 0
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 (list; graph; refs; listen; history; text; internal format)
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: A079446 A283262 A115975 * A087797 A280619 A282136

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

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Last modified November 13 11:09 EST 2018. Contains 317133 sequences. (Running on oeis4.)