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Numbers k that are multiples of 3 and also A059975(k) is a multiple of 3, where A059975 is fully additive with a(p) = p-1.
3

%I #13 Jun 06 2024 09:47:43

%S 6,15,27,33,36,42,48,51,69,78,87,90,105,114,120,123,141,159,162,177,

%T 186,189,195,198,213,216,222,225,231,249,252,258,264,267,285,288,294,

%U 300,303,306,321,336,339,351,357,366,384,393,402,405,408,411,414,429,438,447,465,468,474,483,495,501,513,519,522,537

%N Numbers k that are multiples of 3 and also A059975(k) is a multiple of 3, where A059975 is fully additive with a(p) = p-1.

%C A multiplicative semigroup: if m and n are in the sequence, then so is m*n.

%H Antti Karttunen, <a href="/A373384/b373384.txt">Table of n, a(n) for n = 1..10000</a>

%e 6 = 2*3 is present as A059975(6) = (2-1)+(3-1) = 1+2 = 3 is also a multiple of 3.

%e 27 = 3*3*3 is present as A059975(27) = (3-1)+(3-1)+(3-1) = 2+2+2 = 6 is also a multiple of 3.

%o (PARI) isA373384 = A373383;

%Y Positions of multiples of 3 in A373368.

%Y Cf. A059975, A373383 (characteristic function).

%Y Intersection of A008585 and A373385.

%K nonn

%O 1,1

%A _Antti Karttunen_, Jun 06 2024