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Numbers k for which A335884(k) = 2.
1

%I #9 Jul 17 2020 22:57:59

%S 5,7,9,10,14,18,20,28,36,40,56,72,80,112,144,160,224,288,320,448,576,

%T 640,896,1152,1280,1792,2304,2560,3584,4608,5120,7168,9216,10240,

%U 14336,18432,20480,28672,36864,40960,57344,73728,81920,114688,147456,163840,229376,294912,327680,458752,589824,655360,917504,1179648,1310720

%N Numbers k for which A335884(k) = 2.

%C Numbers n such that when we start from k = n, and apply in any combination the nondeterministic maps k -> k - k/p and k -> k + k/p, (where p can be any of the odd prime factors of k), a power of 2 will appear no later than after two such steps, and on some of the combinations a power of 2 will appear after exactly two steps.

%o (PARI)

%o A335884(n) = { my(f=factor(n)); sum(k=1,#f~,if(2==f[k,1],0,f[k,2]*(1+max(A335884(f[k,1]-1),A335884(f[k,1]+1))))); };

%o isA336122(n) = (2==A335884(n));

%Y Cf. A335884.

%Y Cf. also A334102, A335882, A335912.

%K nonn

%O 1,1

%A _Antti Karttunen_, Jul 09 2020