A192687 - OEIS

%I #21 Feb 27 2020 07:04:43

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

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

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

%N Male-female differences: a(n) = A005378(n) - A005379(n).

%C 0 <= a(n) <= 1;

%C for n > 0: a(n) = A010056(n-1), a(A001690(n)-1) = 0, a(A000071(n)) = 1.

%D Hofstadter, "Goedel, Escher, Bach", p. 137.

%H Charles R Greathouse IV, <a href="/A192687/b192687.txt">Table of n, a(n) for n = 0..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/HofstadterMale-FemaleSequences.html">Hofstadter Male-Female Sequences.</a>

%H <a href="/index/Ho#Hofstadter">Index entries for Hofstadter-type sequences</a>

%H <a href="/index/Go#GEB">Index entries for sequences from "Goedel, Escher, Bach"</a>

%o (Haskell)

%o a192687 n = a192687_list !! n

%o a192687_list = zipWith (-) females males where

%o    females = 1 : zipWith (-) [1..] (map (males !!) females)

%o    males = 0 : zipWith (-) [1..] (map (females !!) males)

%o (PARI) a(n)=my(k=(n+1)^2); k+=(k+1)<<2; issquare(k) || issquare(k-8) \\ _Charles R Greathouse IV_, Nov 07 2014

%Y Cf. A000071, A001690, A005378, A005379, A010056, A104162.

%K nonn,easy

%O 0

%A _Reinhard Zumkeller_, Jul 12 2011