A323069 - OEIS

%I #8 Jan 07 2019 11:13:18

%S 0,0,0,0,0,1,0,1,0,0,0,2,0,0,1,1,0,2,0,0,0,0,0,3,0,0,0,0,0,3,0,1,0,0,

%T 1,4,0,0,0,1,0,1,0,0,1,0,0,4,0,0,0,0,0,2,0,1,0,0,0,4,0,0,0,1,0,1,0,0,

%U 0,2,0,5,0,0,1,0,0,1,0,1,0,0,0,2,0,0,0,1,0,4,0,0,0,0,0,4,0,0,1,0,0,1,0,1,2

%N Number of divisors d of n such that A049820(d) > 1 and A049820(d) is also a divisor of n.

%H Antti Karttunen, <a href="/A323069/b323069.txt">Table of n, a(n) for n = 1..10080</a>

%F Sum_{d|n} [A049820(d) > 1 and A049820(d)|n], where [ ] is the Iverson bracket.

%F a(n) <= A323068(n).

%F a(n) >= A322358(n).

%o (PARI) A323069(n) = sumdiv(n,d,my(t=(d-numdiv(d))); ((t>1)&&!(n%t)));

%Y Cf. A000005, A049820, A322358, A323068.

%K nonn

%O 1,12

%A _Antti Karttunen_, Jan 05 2019