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 A362130 a(n) = A000005(A360179(n)) mod 2. 2

%I #8 Apr 14 2023 11:36:05

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

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

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

%N a(n) = A000005(A360179(n)) mod 2.

%H Michael De Vlieger, <a href="/A362130/b362130.txt">Table of n, a(n) for n = 1..40000</a>

%H Michael De Vlieger, <a href="/A362130/a362130.png">4096 X 4096 pixel bitmap of a(n)</a>, n = 1..2^24.

%t nn = 120;

%t c[_] := False; h[_] := 0; f[n_] := DivisorSigma[0, n];

%t a[1] = j = u = 1;

%t {1}~Join~Reap[Do[

%t If[c[j],

%t k = j + f[u]; h[j]++; h[u]--,

%t k = f[j]; c[j] = True; h[j]++ ];

%t u = Min[u, j]; Set[{a[n], j}, {k, k}]; While[h[u] == 0, u++];

%t Sow[Mod[f[k], 2]], {n, 2, nn}], n]][[-1, -1]]

%Y Cf. A000005, A360179, A362129.

%K nonn

%O 1

%A _Michael De Vlieger_, Apr 09 2023

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Last modified June 21 19:43 EDT 2024. Contains 373558 sequences. (Running on oeis4.)