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a(n) = 1 if A326042(k) < k, otherwise 0.
6

%I #8 Nov 15 2021 10:02:47

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

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

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

%N a(n) = 1 if A326042(k) < k, otherwise 0.

%H Antti Karttunen, <a href="/A348737/b348737.txt">Table of n, a(n) for n = 1..65537</a>

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

%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); \\ From A003961

%o A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};

%o A326042(n) = A064989(sigma(A003961(n)));

%o A348737(n) = (A326042(n)<n);

%Y Characteristic function of A348738.

%Y Cf. A000203, A003961, A064989, A326042.

%K nonn

%O 1

%A _Antti Karttunen_, Nov 02 2021