A337544 - OEIS

%I #6 Sep 22 2020 02:50:35

%S 1,1,3,3,5,1,9,9,15,3,11,3,15,7,13,27,17,5,21,9,25,9,27,9,35,13,75,21,

%T 29,-9,35,81,31,15,43,15,39,19,43,27,41,-5,45,27,65,25,51,27,99,21,49,

%U 39,57,25,53,63,61,27,59,-27,65,33,125,243,73,-3,69,45,79,9,71,45,77,37,91,57,97,1,81,81,375,39,87,-15,83

%N a(n) = 2*phi(A003961(n)) - A003961(n).

%H Antti Karttunen, <a href="/A337544/b337544.txt">Table of n, a(n) for n = 1..16384</a>

%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>

%F a(n) = A083254(A003961(n)).

%F a(n) = 2*A003972(n) - A003961(n).

%o (PARI)

%o A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f);

%o A337544(n) = (2*eulerphi(A003961(n)) - A003961(n));

%Y Cf. A000010, A003961, A003972, A083254.

%K sign

%O 1,3

%A _Antti Karttunen_, Sep 21 2020