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%I #15 Oct 23 2017 20:03:33
%S 169,1219,1339,1966,3959,7519,11569,17845,35579,37391,38579,77593,
%T 94249,94319,95299,96139,97271,97969,99691,106159,107629,115069,
%U 137533,150071,168505,188297,247589,339629,345911,352829,362771,363191,365399,370259,381779,382043
%N Composite numbers k = concat(MSD(k),x) such that k' = x', where k' is the arithmetic derivative of k.
%H Paolo P. Lava, <a href="/A293477/b293477.txt">Table of n, a(n) for n = 1..150</a>
%e 169' = 69' = 26, so 169 is a term.
%e 3959' = 959' = 144, so 3959 is a term.
%p with(numtheory): P:=proc(q) local a,k,n,p,x,y; for n from 2 to q do
%p if not isprime(n) then x:=n mod 10^(ilog10(n)); a:=x*add(op(2, p)/op(1,p), p=ifactors(x)[2]);
%p if n*add(op(2, p)/op(1, p), p=ifactors(n)[2])=a then print(n); fi; fi; od; end: P(10^6);
%Y Cf. A000030 (MSD), A003415 (arithmetic derivative).
%K nonn,base,easy
%O 1,1
%A _Paolo P. Lava_, Oct 10 2017
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