A232731 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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

a(1) = A232729(1), a(n) = A232729(n) + A232730(n-1), n > 1.

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

Cf. A190481, A232729, A232730.

Sequence in context: A202790 A231833 A028455 * A215792 A280358 A114480

Adjacent sequences: A232728 A232729 A232730 * A232732 A232733 A232734

KEYWORD

nonn,easy

AUTHOR

Lars Blomberg, Nov 29 2013

STATUS

approved