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A373494 Numbers k for which A059975(k) and A003415(k) are both multiples of 3, where A059975 is fully additive with a(p) = p-1, and A003415 is the arithmetic derivative.

%I A373494 #7 Jun 10 2024 17:45:25
%S A373494 1,8,20,27,36,44,50,64,68,90,92,110,116,125,160,162,164,170,188,189,
%T A373494 198,212,216,225,230,236,242,252,275,284,288,290,306,332,343,351,352,
%U A373494 356,374,400,404,405,410,414,425,428,452,468,470,495,506,512,513,522,524,530,540,544,548,575,578,590,596,605,630,637
%N A373494 Numbers k for which A059975(k) and A003415(k) are both multiples of 3, where A059975 is fully additive with a(p) = p-1, and A003415 is the arithmetic derivative.
%C A373494 A multiplicative semigroup: if m and n are in the sequence, then so is m*n.
%H A373494 Antti Karttunen, <a href="/A373494/b373494.txt">Table of n, a(n) for n = 1..10000</a>
%o A373494 (PARI) isA373494 = A373493;
%Y A373494 Cf. A003415, A059975, A373492 (subsequence), A373493 (characteristic function).
%Y A373494 Positions of multiples of 3 in A373378.
%Y A373494 Intersection of A373385 and A327863.
%K A373494 nonn
%O A373494 1,2
%A A373494 _Antti Karttunen_, Jun 10 2024