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

Author

Patrick De Geest, Mar 15 1999

Keywords

• nonn
• base
• easy

Links

• Eric Weisstein's World of Mathematics, Square Number
• Index entries for linear recurrences with constant coefficients, signature (0,10).

Crossrefs

Cf. A000290, A036507.

Programs

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

Mathematica

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

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)

Extensions

More terms from Lior Manor, Jul 02 2001

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