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A064900 Semiprimes p1*p2 such that p2 mod p1 = 2. 4

%I

%S 15,33,35,51,69,85,87,123,141,143,159,161,177,185,213,235,249,259,267,

%T 303,321,323,335,339,393,411,447,485,501,519,533,535,537,553,573,591,

%U 635,681,685,699,717,749,753,771,785,789,807,835,843,869,871,879,899

%N Semiprimes p1*p2 such that p2 mod p1 = 2.

%H John Cerkan, <a href="/A064900/b064900.txt">Table of n, a(n) for n = 1..10000</a>

%t okQ[n_] := Module[{p, e}, {p, e} = Transpose[FactorInteger[n]]; e == {1, 1} && Mod[p[[2]], p[[1]]] == 2]; Select[Range[1000], okQ]

%o (PARI) isok(n) = (bigomega(n)==2) && (f=factor(n)) && (#f~ == 2) && ((f[2,1] % f[1,1]) == 2); \\ _Michel Marcus_, May 20 2017

%Y Cf. A001358 (p2 mod p1 = 0), A064899-A064911.

%K nonn

%O 1,1

%A _Patrick De Geest_, Oct 13 2001

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Last modified June 12 19:31 EDT 2021. Contains 344960 sequences. (Running on oeis4.)