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%I #18 Feb 24 2024 01:03:14
%S 1,0,0,4,0,12,0,216,36,40,0,900,0,84,120,38416,0,3600,0,4860,252,220,
%T 0,223608,400,312,13824,14196,0,18900,0,24300000,660,544,840,1258884,
%U 0,684,936,1920520,0,54600,0,58212,70560,1012,0,201485520,1764,97200
%N Replace all prime factors p of n with n-p.
%C a(n)=0 iff n is prime.
%H Paolo P. Lava, <a href="/A072194/b072194.txt">Table of n, a(n) for n = 1..10000</a>
%e a(18) = a(2*3*3) = (18-2)*(18-3)*(18-3) = 16*15*15 = 3600.
%t Join[{1},Table[Times@@(n-#&/@Flatten[Table[#[[1]],#[[2]]]&/@FactorInteger[ n]]),{n,2,50}]] (* _Harvey P. Dale_, Dec 04 2018 *)
%o (PARI) a(n) = {my(f = factor(n)); for (k=1, #f~, f[k, 1] = n - f[k, 1];); factorback(f);} \\ _Michel Marcus_, Mar 22 2018
%K nonn
%O 1,4
%A _Reinhard Zumkeller_, Jul 02 2002
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