A051832 Numbers k such that (2*10^(5*k) - 10^(4*k) + 2*10^(3*k) + 10^(2*k) + 10^k + 1)/3 is prime.

0, 1, 7, 133

Offset

1,3

Comments

The Baxter-Hickerson function provides a number whose cube lacks zeros.

The next term is > 4400. - Jason Earls, Sep 10 2005

The next term is > 20000 (found using pfgw64). - Patrick De Geest, Jul 22 2012

Links

Table of n, a(n) for n=1..4.

Ed Pegg, Jr., Fun with numbers.

Eric Weisstein's World of Mathematics, Baxter-Hickerson Function.

Maple

f := n->(2*10^(5*n) - 10^(4*n) + 2*10^(3*n) + 10^(2*n) + 10^n + 1)/3;

Prog

(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

Crossrefs

Cubes: A052044, A052045, A051750, A051751, A051833. Squares: A052040, A052041, A052042, A052043.

Sequence in context: A220321 A247597 A305955 * A103050 A110111 A245318

Adjacent sequences: A051829 A051830 A051831 * A051833 A051834 A051835

Keyword

hard,nonn

Author

G. L. Honaker, Jr., Dec 11 1999

Status

approved