OFFSET
1,8
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = n - A001414(n).
a(n) = 0 if n is prime or if n = 4. - Alonso del Arte, Jul 31 2018
EXAMPLE
a(6) = 1 because 6 = 2 * 3, sopfr(6) = 2 + 3 = 5 and 6 - 5 = 1.
MAPLE
a:= n-> n-add(i[1]*i[2], i=ifactors(n)[2]):
seq(a(n), n=1..100); # Alois P. Heinz, Aug 07 2015
MATHEMATICA
Join[{1}, Table[n - Total[Times@@@FactorInteger[n]], {n, 2, 80}]] (* Harvey P. Dale, Sep 20 2011 *)
PROG
(PARI) A075255(n)=n-sum(i=1, #n=factor(n)~, n[1, i]*n[2, i]) \\ M. F. Hasler, Oct 31 2008
(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
(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
(Python)
from sympy import factorint
def A075255(n): return n - sum(factorint(n, multiple=True)) # Chai Wah Wu, May 19 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Sep 10 2002
STATUS
approved