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%I #24 Feb 17 2024 10:30:58
%S 2,42,642,8642,108642,12108642,1412108642,161412108642,18161412108642,
%T 2018161412108642,222018161412108642,24222018161412108642,
%U 2624222018161412108642,282624222018161412108642,30282624222018161412108642,3230282624222018161412108642
%N Concatenate first n even numbers in reverse order.
%C F. Smarandache conjectures that a(n) is never a perfect power (see link sequence 163 page 80). - _Michel Marcus_, Mar 03 2014
%D Mihaly Bencze [Beneze], L. Tutescu, Some Notions and Questions in Number Theory, Sequence 4.
%H Florentin Smarandache, <a href="http://arxiv.org/abs/math/0604019">Sequences of Numbers Involved in Unsolved Problems</a>, arXiv:math/0604019 [math.GM], 2006.
%t Join[{s = 2}, Table[s = FromDigits[Flatten[IntegerDigits[{n, s}]]], {n, 4, 26, 2}]] (* _Jayanta Basu_, Jul 14 2013 *)
%t Table[FromDigits[Flatten[IntegerDigits/@Range[2n,2,-2]]],{n,20}] (* _Harvey P. Dale_, Jun 11 2017 *)
%o (PARI) a(n) = concat(vector(n, i, Str(2*n - (2*i)+2))); \\ _Michel Marcus_, Mar 03 2014
%K nonn,base,easy
%O 1,1
%A M. I. Petrescu (mipetrescu(AT)yahoo.com)
%E More terms from _Michel Marcus_, Mar 03 2014
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