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%I #8 Nov 10 2021 18:26:07
%S 1,3,4,5,7,9,11,12,13,15,16,17,19,21,23,25,28,29,31,33,35,36,37,39,41,
%T 43,45,47,48,49,51,52,53,55,59,61,63,64,67,69,71,73,75,76,77,79,81,83,
%U 84,85,89,91,93,95,97,101,103,105,107,109,111,112,113,115,117,119,121,123,124,125,127,129,131,133,137,139
%N Numbers k such that sigma(k) and A003961(k) are relatively prime, where A003961(n) is fully multiplicative function with a(prime(k)) = prime(k+1).
%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%o (PARI)
%o A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
%o isA349165(n) = (1==gcd(sigma(n), A003961(n)));
%Y Cf. A000203, A003961.
%Y Positions of ones in A342671, and also in A349163.
%Y Cf. A349166 (complement), A349167 (characteristic function).
%K nonn
%O 1,2
%A _Antti Karttunen_, Nov 09 2021
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