A133264 Smallest number whose sum of digits is 3n+1.

1, 4, 7, 19, 49, 79, 199, 499, 799, 1999, 4999, 7999, 19999, 49999, 79999, 199999, 499999, 799999, 1999999, 4999999, 7999999, 19999999, 49999999, 79999999, 199999999, 499999999, 799999999, 1999999999, 4999999999, 7999999999

Offset

0,2

Links

Table of n, a(n) for n=0..29.

Index entries for linear recurrences with constant coefficients, signature (1, 0, 10, -10).

Formula

a(n) = a(n-1) + 10*a(n-3) - 10*a(n-4). - Chai Wah Wu, May 25 2016

G.f.: (1 + 3*x + 3*x^2 + 2*x^3)/(1 - x - 10*x^3 + 10*x^4). - Michael De Vlieger, May 25 2016

Mathematica

LinearRecurrence[{1, 0, 10, -10}, {1, 4, 7, 19}, 31] (* or *)
CoefficientList[Series[(1 + 3 x + 3 x^2 + 2 x^3)/(1 - x - 10 x^3 + 10 x^4), {x, 0, 30}], x] (* Michael De Vlieger, May 25 2016 *)

Crossrefs

Sequence in context: A190646 A220011 A305034 * A253208 A275389 A127415

Adjacent sequences: A133261 A133262 A133263 * A133265 A133266 A133267

Keyword

nonn,base

Author

Paul Curtz, Oct 16 2007

Status

approved