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Replace nonprimes in A005185 with zeros.
0

%I #6 Mar 31 2017 21:22:34

%S 0,0,2,3,3,0,5,5,0,0,0,0,0,0,0,0,0,11,11,0,0,0,0,0,0,0,0,0,0,0,0,17,

%T 17,0,0,19,0,0,0,0,23,23,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

%U 31,0,0,0,0,0,37,0,0,0,0,0,0,0,41,43,0,43,43,0,0,0,47,47,0,0,0,0,0,0,0,0,41

%N Replace nonprimes in A005185 with zeros.

%F a(n) = if Hofstadter[n] is prime then Hofstadter[n] else zero

%t digits = 200 Hofstadter[n_Integer? Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n - 1]] + Hofstadter[n - Hofstadter[n - 2]] Hofstadter[0] = Hofstadter[1] = 1 b = Table[If[PrimeQ[ Hofstadter[n]] == True, Hofstadter[n], 0], {n, 0, digits - 1}]

%Y Cf. A005185.

%K nonn

%O 0,3

%A _Roger L. Bagula_, Mar 10 2005