A109867 - OEIS

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A109867

a(1) = 12; for n >= 1, a(n+1) = abs((a(n) + R(a(n))) * (a(n) - R(a(n)))), where R(k) is the digit reversal of k.

12, 297, 539055, 12949081200, 167631138529627443759, 888408727567955042239409874101472777521040, 787659989217062162749912989661115208857840881836480202901460330472578518132645989056

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

OFFSET

1,1

COMMENTS

The next term has 168 digits. - Harvey P. Dale, Dec 01 2017

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

a(2) = (12 + 21)*(21 - 12) = 297.

MATHEMATICA

a = {12}; For[n = 2, n < 10, n++, AppendTo[a, Abs[(a[[ -1]] + FromDigits[Reverse[IntegerDigits[a[[ -1]]]]])* (a[[ -1]] - FromDigits[Reverse[IntegerDigits[a[[ -1]]]]])]]]; a (* Stefan Steinerberger, Jun 05 2007 *)

NestList[(#+IntegerReverse[#])Abs[#-IntegerReverse[#]]&, 12, 10] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 01 2017 *)

CROSSREFS

Sequence in context: A223011 A245915 A377631 * A326437 A303068 A014130

Adjacent sequences: A109864 A109865 A109866 * A109868 A109869 A109870

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Jul 09 2005

EXTENSIONS

Corrected and extended by Stefan Steinerberger, Jun 05 2007

Definition corrected by Georg Fischer, Sep 09 2022

STATUS

approved