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
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
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