A083812 4n-1 is the digit reversal of n-1.

18, 198, 1998, 19998, 199998, 1999998, 19999998, 199999998, 1999999998, 19999999998, 199999999998, 1999999999998, 19999999999998, 199999999999998, 1999999999999998, 19999999999999998, 199999999999999998, 1999999999999999998, 19999999999999999998

Offset: 1

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003

Keywords

• base
• nonn

Comments

1. a(n) = 18 + 180 + 1800+ ...+ up to n terms. a(n) = sum of n terms of the geometric progression with the first term 18 and common ratio 10. 2. a(n) = 18*A000042(n).( the unary sequence).

Examples

			18 -1 = 17, 4*18 - 1 = 71.
		

Links

• Index entries for linear recurrences with constant coefficients, signature (11, -10).

Crossrefs

Cf. A000042, A083811.

Programs

Mathematica

Accumulate[NestList[10#&,18,20]] (* or *) LinearRecurrence[{11,-10},{18,198},20] (* Harvey P. Dale, Apr 24 2015 *)

Formula

a(n) = 2*(10^n - 1).

a(1)=18, a(2)=198, a(n)=11*a(n-1)-10*a(n-2). - Harvey P. Dale, Apr 24 2015

Extensions

Corrected and extended by Harvey P. Dale, Apr 24 2015