login
Lcm[{ad(n)}], i.e. the least common multiple of the anti-divisors of n.
2

%I #23 Feb 24 2024 01:10:11

%S 2,3,6,4,30,15,6,84,42,40,90,36,30,33,2310,420,78,312,42,180,90,112,

%T 3570,204,990,25080,114,60,126,4095,4290,276,4830,24,150,23100,6006,

%U 432,54,7140,14790,696,8190,33852,17670,3040,1386,1980,102,840,210,36,12210

%N Lcm[{ad(n)}], i.e. the least common multiple of the anti-divisors of n.

%C See A066272 for definition of anti-divisor. Offset is 3 because 1 and 2 have no anti-divisors.

%H Paolo P. Lava, <a href="/A096357/b096357.txt">Table of n, a(n) for n = 3..10000</a>

%e The anti-divisors of 7 are 2,3 and 5, so a(7)=30.

%e The anti-divisors of 9 are 2 and 6, so a(9)=6.

%t a096357[n_] := Module[{ad},

%t ad := Cases[Range[2, n - 1], _?(Abs[Mod[n, #] - #/2] < 1 &)];

%t If[Length[ad] == 0, 0, LCM @@ ad]] (* _Michael De Vlieger_, Aug 09 2014*)

%o (Python)

%o from sympy import lcm

%o A096357 = [lcm([d for d in range(2,n,2) if n%d and not 2*n%d]+[d for d in range(3,n,2) if n%d and 2*n%d in [d-1,1]]) for n in range(3,10**5)] # _Chai Wah Wu_, Aug 09 2014

%Y Cf. A066272.

%K nonn

%O 3,1

%A _Jon Perry_, Jun 30 2004

%E Offset changed by _N. J. A. Sloane_, Aug 22 2014