A017964 Powers of sqrt(20) rounded down.

1, 4, 20, 89, 400, 1788, 8000, 35777, 160000, 715541, 3200000, 14310835, 64000000, 286216701, 1280000000, 5724334022, 25600000000, 114486680447, 512000000000, 2289733608959, 10240000000000, 45794672179195

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..700

Formula

a(n) = floor(sqrt(20^n)). - Vincenzo Librandi, Jun 24 2011

Mathematica

Floor[(Sqrt[20])^Range[0, 30]] (* Harvey P. Dale, Mar 13 2017 *)

Prog

(PARI) a(n)=sqrtint(20^n) \\ Charles R Greathouse IV, Nov 18 2011

Crossrefs

Sequence in context: A196953 A093357 A027156 * A017965 A180284 A065180

Adjacent sequences: A017961 A017962 A017963 * A017965 A017966 A017967

Keyword

nonn

Author

N. J. A. Sloane

Status

approved