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a(n) = 1 if for all proper divisors d of n, A011772(d) < A011772(n), otherwise 0.
8

%I #11 Jun 30 2021 19:48:23

%S 1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,1,1,0,1,1,0,1,1,0,1,0,1,0,1,1,1,1,1,0,

%T 1,0,1,1,0,0,1,1,1,1,1,1,1,1,1,0,1,1,1,1,0,1,0,0,1,0,1,1,1,1,1,0,1,0,

%U 1,1,1,1,1,0,0,1,1,0,1,1,1,0,1,1,1,1,1,0,1,1,1,0,0,1,1,0,1,0,1,0,1,1,1,1,0

%N a(n) = 1 if for all proper divisors d of n, A011772(d) < A011772(n), otherwise 0.

%H Antti Karttunen, <a href="/A344880/b344880.txt">Table of n, a(n) for n = 1..65537</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F a(n) >= A010055(n) for all n.

%o (PARI)

%o A011772(n) = { if(n==1, return(1)); my(f=factor(if(n%2, n, 2*n)), step=vecmax(vector(#f~, i, f[i, 1]^f[i, 2]))); forstep(m=step, 2*n, step, if(m*(m-1)/2%n==0, return(m-1)); if(m*(m+1)/2%n==0, return(m))); }; \\ From A011772

%o A344880(n) = { my(x=A011772(n)); fordiv(n,d,if(A011772(d)==x, return(d==n))); };

%Y Characteristic function of A344881.

%Y Cf. A010055, A011772, A344881, A344882, A344884, A344885.

%K nonn

%O 1

%A _Antti Karttunen_, Jun 01 2021