A212912 - OEIS

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A212912

Numbers k such that 3^(m+3) == 9 (mod m) where m = (k-1)^2 - 1.

3, 5, 7, 11, 17, 37, 47, 53, 67, 97, 101, 121, 211, 257, 367, 379, 457, 617, 911, 1091, 1237, 1297, 1361, 1549, 2003, 2557, 2851, 2897, 3517, 3733, 4201, 4357, 5209, 6481, 7621, 8461, 8647, 8689, 10253, 10457, 10631, 11953, 13729, 14401, 14951, 17431, 17837

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Composites begin: 121, 108781, 155365, 267547, 2774521, 3166087, 3225601, 4907701, 8341201, 10712857, 11035921, 13216141, 17559829, 21708961, 29641921, 31116241, 31150351, ... are all composite terms congruent to 1 (mod 3)?

LINKS

Table of n, a(n) for n=1..47.

MATHEMATICA

Join[{3}, Select[Range[4, 20000], PowerMod[3, (#-1)^2+2, (#-1)^2-1]==9&]] (* Harvey P. Dale, Dec 07 2019 *)

PROG

(PARI) for(n=2, 1000, m=n^2-1; if(Mod(3, m)^(m+3)==9, print(n+1)));

CROSSREFS

Sequence in context: A116457 A037155 A282632 * A356751 A038944 A124081

Adjacent sequences: A212909 A212910 A212911 * A212913 A212914 A212915

KEYWORD

nonn

AUTHOR

Alzhekeyev Ascar M, May 30 2012

EXTENSIONS

More terms from Harvey P. Dale, Dec 07 2019

STATUS

approved