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%I #30 Mar 04 2023 11:52:23
%S 0,1,7,133
%N Numbers k such that (2*10^(5*k) - 10^(4*k) + 2*10^(3*k) + 10^(2*k) + 10^k + 1)/3 is prime.
%C The Baxter-Hickerson function provides a number whose cube lacks zeros.
%C The next term is > 4400. - _Jason Earls_, Sep 10 2005
%C The next term is > 20000 (found using pfgw64). - _Patrick De Geest_, Jul 22 2012
%H Ed Pegg, Jr., <a href="http://www.mathpuzzle.com/numbers.html">Fun with numbers</a>.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Baxter-HickersonFunction.html">Baxter-Hickerson Function</a>.
%p f := n->(2*10^(5*n) - 10^(4*n) + 2*10^(3*n) + 10^(2*n) + 10^n + 1)/3;
%o (PARI) is(n)=isprime((2*10^(5*n)-10^(4*n)+2*10^(3*n)+10^(2*n)+10^n+1)/3) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y Cubes: A052044, A052045, A051750, A051751, A051833. Squares: A052040, A052041, A052042, A052043.
%K hard,nonn
%O 1,3
%A _G. L. Honaker, Jr._, Dec 11 1999
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