A085928 - OEIS

A085928

a(1) = 1, a(2) = 2, then the absolute difference of the concatenation of two previous terms and its digit reversal.

1, 2, 9, 63, 594, 14058, 25627437, 5941439657604, 150482558208133815048, 2463743660424402357955859435526447, 5941429767504259381561776919813218438160375943419757604, 16038354830713282603922637536703240576965473072533033395669335536367159371668297243716038

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OFFSET

1,2

COMMENTS

a(n) is a multiple of 99 for n > 4. Conjecture: The sequence has finitely many nonzero terms. (This would happen when the concatenation of two successive terms becomes a palindrome and the next term is 0.)

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

a(1) = 1, a(2) = 2, a(3) = |12-21| = 9, a(4) = |29-92| = 63, a(5) = |963-369| = 594, a(6) = |63594 - 49536| = 14058, a(7) = |59418018 - 81081495| = 21663477, ...

MATHEMATICA

nxt[{a_, b_}]:=Module[{id=Join[IntegerDigits[a], IntegerDigits[b]]}, {b, Abs[ FromDigits[ id]- FromDigits[Reverse[id]]]}]; Transpose[NestList[nxt, {1, 2}, 12]][[1]] (* Harvey P. Dale, Nov 30 2014 *)

CROSSREFS

Sequence in context: A166886 A212413 A003577 * A130169 A218672 A253109

Adjacent sequences: A085925 A085926 A085927 * A085929 A085930 A085931

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy and Jason Earls, Jul 13 2003

EXTENSIONS

Corrected and extended by Mark Hudson (mrmarkhudson(AT)hotmail.com), Jul 23 2004

More terms from David Wasserman, Feb 11 2005

One more term (a(12)) from Harvey P. Dale, Nov 30 2014

STATUS

approved