A232731 Number of numbers that yield an n-digit number after Reverse and Add!.
4, 50, 450, 4590, 45405, 454950, 4544550, 45454500, 454495500, 4545045000, 45449955000, 454500450000, 4544999550000, 45450004500000, 454499995500000, 4545000045000000, 45449999955000000, 454500000450000000, 4544999999550000000, 45450000004500000000
Offset: 1
Links
- Colin Barker, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (10,10,-100).
Programs
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Mathematica
LinearRecurrence[{10,10,-100},{4,50,450,4590,45405},20] (* Harvey P. Dale, Sep 22 2017 *) -
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
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)
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