A323513 - OEIS

%I #7 Jan 18 2019 20:54:57

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

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

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

%N a(n) = 1 if n and phi(n) share the same prime signature, 0 otherwise.

%C Characteristic function for A300216.

%H Antti Karttunen, <a href="/A323513/b323513.txt">Table of n, a(n) for n = 1..100000</a>

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

%F a(n) = [A046523(n) == A046523(A000010(n))], where [ ] is the Iverson bracket.

%o (PARI)

%o A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523.

%o A323513(n) = (A046523(n) == A046523(eulerphi(n)));

%Y Cf. A000010, A046523, A277906, A300216.

%Y Cf. also A318893.

%K nonn

%O 1

%A _Antti Karttunen_, Jan 18 2019