A083818 Numbers n such that 2n-1 is the digit reversal of n.

1, 37, 397, 3997, 39997, 399997, 3999997, 39999997, 399999997, 3999999997, 39999999997, 399999999997, 3999999999997, 39999999999997, 399999999999997, 3999999999999997, 39999999999999997, 399999999999999997, 3999999999999999997, 39999999999999999997

Offset

1,2

Comments

a(n) = 1 + 36 + 360 + 3600 + 36000 + ..., for a total of n terms. a(n) = 1 + sum of first n-1 terms of the geometric progression with first term 36 and common ratio 10. a(n) = 1 + 36*A000042(n-1) (the unary sequence).

Links

Table of n, a(n) for n=1..20.

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

Formula

a(n) = 4*10^(n-1) - 3.

Example

2*37 - 1 = 73.

Crossrefs

Cf. A083811, A083812, A083813.

Digit reversals are A169830.

Sequence in context: A264626 A201789 A115926 * A090023 A254682 A232251

Adjacent sequences: A083815 A083816 A083817 * A083819 A083820 A083821

Keyword

base,easy,nonn

Author

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

Extensions

a(1)=1 inserted by David Radcliffe, Jul 25 2015

Status

approved