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A070823 a(1)=0, a(1)=1, a(n+2)=abs(concatenate(a(n+1)a(n))-concatenate(a(n)a(n+1)). 0
0, 1, 9, 72, 243, 47871, 23523372, 2434786275501, 8244905115337247871, 58101188398354233807319449027630, 243478627550182449084906698122045988902204111779759, 33753325643335988898828779215425644588407139004473126805509723691755094884662752129 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n)==0 mod 3 if n>2. Is a(n) always of the form 2^a*3^b*b(n) where b(n) is a squarefree number? As example : a(12)=3^12*11*192263*58877057*6250682413*588631991107100965223

LINKS

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

EXAMPLE

a(2)=72 a(3)=243 then a(4)=abs(24372-72243)=47871

MATHEMATICA

nxt[{a_, b_}]:=Module[{ida=IntegerDigits[a], idb=IntegerDigits[b]}, {b, Abs[ FromDigits[ Join[ ida, idb]]-FromDigits[Join[idb, ida]]]}]; Transpose[ NestList[ nxt, {0, 1}, 13]] [[1]] (* Harvey P. Dale, Sep 19 2014 *)

CROSSREFS

Sequence in context: A064201 A244728 A069978 * A073988 A005778 A288351

Adjacent sequences:  A070820 A070821 A070822 * A070824 A070825 A070826

KEYWORD

easy,nonn,base

AUTHOR

Benoit Cloitre, May 15 2002

EXTENSIONS

One more term (a(12)) from Harvey P. Dale, Sep 19 2014

STATUS

approved

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Last modified June 1 18:43 EDT 2020. Contains 334762 sequences. (Running on oeis4.)