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Numbers k such that prime(2*k) - prime(k) == 0 (mod k).
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%I #24 Jan 14 2024 14:19:37

%S 1,2,4,6,18,42,44,49,246,257,259,272,283,294,25284,62648,62664,62673,

%T 62700,62701,158706,404835,404859,405119,405448,405451,2630908,

%U 2630929,2631249,2631303,2631368,2631414,2631509,2631517,2631576,2631666,17405852,44932936

%N Numbers k such that prime(2*k) - prime(k) == 0 (mod k).

%e prime(2*2) - prime(2) = 7 - 3 = 4 that is equal to 0 mod 2, so 2 is in the sequence.

%o (PARI) isok(n) = (prime(2*n)-prime(n)) % n == 0; \\ _Michel Marcus_, Nov 20 2013

%Y Cf. A072473.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Jan 24 2002

%E a(15)-a(20) from _Michel Marcus_, Nov 20 2013

%E a(21)-a(38) from _Donovan Johnson_, Nov 20 2013