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a(n) = n - (sum of primes factors of n (with repetition)).
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%I #29 Sep 08 2022 08:45:07

%S 1,0,0,0,0,1,0,2,3,3,0,5,0,5,7,8,0,10,0,11,11,9,0,15,15,11,18,17,0,20,

%T 0,22,19,15,23,26,0,17,23,29,0,30,0,29,34,21,0,37,35,38,31,35,0,43,39,

%U 43,35,27,0,48,0,29,50,52,47,50,0,47,43,56,0,60,0,35,62,53,59,60

%N a(n) = n - (sum of primes factors of n (with repetition)).

%H Alois P. Heinz, <a href="/A075255/b075255.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = n - A001414(n).

%F a(n) = 0 if n is prime or if n = 4. - _Alonso del Arte_, Jul 31 2018

%e a(6) = 1 because 6 = 2 * 3, sopfr(6) = 2 + 3 = 5 and 6 - 5 = 1.

%p a:= n-> n-add(i[1]*i[2], i=ifactors(n)[2]):

%p seq(a(n), n=1..100); # _Alois P. Heinz_, Aug 07 2015

%t Join[{1}, Table[n - Total[Times@@@FactorInteger[n]], {n, 2, 80}]] (* _Harvey P. Dale_, Sep 20 2011 *)

%o (PARI) A075255(n)=n-sum(i=1,#n=factor(n)~,n[1,i]*n[2,i]) \\ _M. F. Hasler_, Oct 31 2008

%o (Magma) [n eq 1 select 1 else n-(&+[p[1]*p[2]: p in Factorization(n)]): n in [1..80]]; // _G. C. Greubel_, Jan 11 2019

%o (Sage) [n - sum(factor(n)[j][0]*factor(n)[j][1] for j in range(0, len(factor(n)))) for n in range(1, 80)] # _G. C. Greubel_, Jan 11 2019

%o (Python)

%o from sympy import factorint

%o def A075255(n): return n - sum(factorint(n,multiple=True)) # _Chai Wah Wu_, May 19 2022

%Y Cf. A001414, A008472, A075254, A075653.

%Y Cf. A145834 (= 0 followed by the nonzero terms of this sequence). - _M. F. Hasler_, Oct 31 2008

%K nonn

%O 1,8

%A _Zak Seidov_, Sep 10 2002