OFFSET
1,1
COMMENTS
A190481 is the number of distinct n-digit numbers after Reverse and Add!.
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (10,10,-100).
FORMULA
From Colin Barker, Mar 20 2017: (Start)
G.f.: x*(4 + 10*x - 90*x^2 - 10*x^3 + 5*x^4) / ((1 - 10*x)*(1 - 10*x^2)).
a(n) = 10*a(n-1) + 10*a(n-2) - 100*a(n-3) for n>5.
(End)
MATHEMATICA
LinearRecurrence[{10, 10, -100}, {4, 50, 450, 4590, 45405}, 20] (* Harvey P. Dale, Sep 22 2017 *)
PROG
(PARI) Vec(x*(4 + 10*x - 90*x^2 - 10*x^3 + 5*x^4) / ((1 - 10*x)*(1 - 10*x^2)) + O(x^30)) \\ Colin Barker, Mar 20 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Lars Blomberg, Nov 29 2013
STATUS
approved