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A054008
n read modulo (number of divisors of n).
5
0, 0, 1, 1, 1, 2, 1, 0, 0, 2, 1, 0, 1, 2, 3, 1, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 3, 4, 1, 6, 1, 2, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 1, 2, 3, 2, 1, 8, 1, 2, 3, 4, 1, 6, 3, 0, 1, 2, 1, 0, 1, 2, 3, 1, 1, 2, 1, 2, 1, 6, 1, 0, 1, 2, 3, 4, 1, 6, 1, 0, 1, 2, 1, 0, 1, 2, 3, 0, 1, 6, 3, 2, 1, 2, 3, 0, 1, 2, 3, 1, 1, 6, 1, 0, 1
OFFSET
1,6
COMMENTS
a(n)=0 iff n is a refactorable number (cf. A033950). - Franz Vrabec, Oct 16 2005
a(A066708(n)) = n and a(m) < n for m < A066708(n). - Reinhard Zumkeller, Sep 17 2014
LINKS
FORMULA
a(n) = n mod tau(n).
MAPLE
[ seq( i mod tau(i), i=1..130) ];
MATHEMATICA
a[n_] := Mod[n, DivisorSigma[0, n]]; Array[a, 105] (* Jean-François Alcover, Sep 19 2017 *)
PROG
(Haskell)
a054008 n = n `mod` a000005 n -- Reinhard Zumkeller, Sep 17 2014
(PARI) a(n) = n % numdiv(n); \\ Michel Marcus, Sep 19 2017
(Python)
from sympy import divisor_count
def A054008(n): return n%divisor_count(n) # Chai Wah Wu, Mar 14 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Asher Auel, Jan 12 2000
STATUS
approved