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A179839 Semiprimes p*q with p < q and 2^p (mod q) == 2^q (mod p). 3
341, 731, 1333, 1387, 1727, 2047, 2701, 3277, 3503, 3763, 4033, 4369, 4681, 5461, 7957, 8321, 9509, 10261, 10669, 13747, 14491, 15709, 17557, 17861, 18721, 19147, 19951, 20737, 23377, 31417, 31609, 31621, 35333, 42799, 43921, 44669, 46979, 49141, 49901, 49981 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The semiprime super-Poulet numbers (semiprimes in A050217) are a subsequence.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

aQ[n_] := Module[{f = FactorInteger[n]}, If[Length[f] == 2 && f[[1, 2]] == f[[2, 2]] == 1, p = f[[1, 1]]; q = f[[2, 1]], Return[False]]; PowerMod[2, p, q] == PowerMod[2, q, p]]; Select[Range[50000], aQ] (* Amiram Eldar, Oct 23 2019 *)

CROSSREFS

Cf. A006881, A179707 (which allows p = q).

Sequence in context: A216170 A321868 A175736 * A172255 A087835 A271221

Adjacent sequences:  A179836 A179837 A179838 * A179840 A179841 A179842

KEYWORD

nonn

AUTHOR

T. D. Noe, Jan 10 2011

STATUS

approved

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Last modified December 12 10:19 EST 2019. Contains 329953 sequences. (Running on oeis4.)