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

1,1

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).

Links

Table of n, a(n) for n=1..19.

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

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

Example

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

Mathematica

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

Crossrefs

Cf. A000042, A083811.

Sequence in context: A060532 A073397 A020920 * A086573 A097515 A177358

Adjacent sequences: A083809 A083810 A083811 * A083813 A083814 A083815

Keyword

base,nonn

Author

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

Extensions

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

Status

approved