A048345 a(n)^2 is the smallest square containing exactly n 0's.

0, 10, 320, 100, 3200, 1000, 32000, 10000, 320000, 100000, 3200000, 1000000, 32000000, 10000000, 320000000, 100000000, 3200000000, 1000000000, 32000000000, 10000000000, 320000000000, 100000000000

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Eric Weisstein's World of Mathematics, Square Number

Index entries for linear recurrences with constant coefficients, signature (0,10).

Formula

From Ralf Stephan, Jul 18 2013: (Start)

a(n) = 10*a(n-2); a(0)=0, a(1)=10, a(2)=320.

G.f.: (10*x + 320*x^2)/(1-10*x^2). (End)

Mathematica

LinearRecurrence[{0, 10}, {0, 10, 320}, 30] (* Harvey P. Dale, Feb 10 2022 *)

Prog

(Magma) a:=[0, 10, 320]; [n le 3 select a[n] else 10*Self(n-2):n in [1..25]]; // Marius A. Burtea, Oct 11 2019

Crossrefs

Cf. A000290, A036507.

Sequence in context: A291561 A302933 A180584 * A325726 A223298 A164055

Adjacent sequences: A048342 A048343 A048344 * A048346 A048347 A048348

Keyword

nonn,base,easy

Author

Patrick De Geest, Mar 15 1999

Extensions

More terms from Lior Manor, Jul 02 2001

a(20) corrected by Georg Fischer, Dec 07 2019

Status

approved