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A134604 Numbers (excluding primes and powers of primes) such that the square mean of their prime factors is a prime (where the square mean of c and d is sqrt((c^2+d^2)/2)). 2

%I #8 Apr 23 2013 00:15:44

%S 119,161,351,595,721,845,959,1045,1081,1241,1323,1375,1547,1792,1855,

%T 2457,2645,2737,3281,3367,3509,3887,3995,4347,4625,4655,4681,5376,

%U 5795,6545,6615,6643,6993,7505,7705,7803,7889,8019,9295,9625,10557,11845

%N Numbers (excluding primes and powers of primes) such that the square mean of their prime factors is a prime (where the square mean of c and d is sqrt((c^2+d^2)/2)).

%C Numbers included in A134601, but not in A025475. a(1)=119 is the minimal number with this property.

%H Hieronymus Fischer, <a href="/A134604/b134604.txt">Table of n, a(n) for n = 1..10000</a>

%e a(2) = 161, since 161 = 7*23 and sqrt((7^2+23^2)/2) = sqrt(289)=17 is a prime.

%e a(10183) = 114383711 = 13*83*227*467 and sqrt((13^2+83^2+227^2+467^2)/4) = sqrt(69169) = 263 is a prime.

%Y Cf. A001597, A025475, A134333, A134344, A134376.

%Y Cf. A134600, A134602, A134608, A134611, A134617, A134619, A134621.

%K nonn

%O 1,1

%A _Hieronymus Fischer_, Nov 11 2007

%E Minor edits by _Hieronymus Fischer_, Apr 22 2013

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Last modified April 16 17:08 EDT 2024. Contains 371749 sequences. (Running on oeis4.)