A373478 - OEIS

A373478

Numbers k such that A001414(k) and A003415(k) are both multiples of 3, where A001414 is the sum of prime factors with repetition, and A003415 is the arithmetic derivative.

%I #13 Jun 08 2024 15:48:04

%S 1,8,9,14,20,26,27,35,38,44,50,62,64,65,68,72,74,77,81,86,92,95,110,

%T 112,116,119,122,125,126,134,143,146,155,158,160,161,164,170,180,185,

%U 188,194,196,203,206,208,209,212,215,216,218,221,230,234,236,242,243,254,275,278,280,284,287,290,299,302,304,305

%N Numbers k such that A001414(k) and A003415(k) are both multiples of 3, where A001414 is the sum of prime factors with repetition, and A003415 is the arithmetic derivative.

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

%H Antti Karttunen, <a href="/A373478/b373478.txt">Table of n, a(n) for n = 1..20000</a>

%o (PARI) isA373478 = A373477;

%Y Cf. A001414, A003415, A373477 (characteristic function).

%Y Positions of multiples of 3 in A373364.

%Y Intersection of A289142 and A327863.

%Y Disjoint union of A373475 and A373479.

%K nonn

%O 1,2

%A _Antti Karttunen_, Jun 07 2024