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%I #17 Sep 08 2022 08:46:10
%S 123,456,789,101112,131415,161718,192021,222324,252627,282930,313233,
%T 343536,373839,404142,434445,464748,495051,525354,555657,585960,
%U 616263,646566,676869,707172,737475,767778,798081,828384,858687,888990,919293,949596,979899
%N Concatenate (3n-2,3n-1,3n).
%p conc3:= (a,b,c) -> c + 10^(1+ilog10(c))*(b+10^(1+ilog10(b))*a):
%p seq(conc3(3*k-2,3*k-1,3*k), k=1..100); # _Robert Israel_, Oct 23 2014
%t FromDigits[Flatten[IntegerDigits/@{#}]]&/@Partition[Range[100], 3] (* _Vincenzo Librandi_, Oct 21 2014 *)
%o (Magma) [Seqint(Intseq(n+1) cat Intseq(n) cat Intseq(n-1)): n in [2..100 by 3]]; // _Vincenzo Librandi_, Oct 21 2014
%o (PARI) a(n)=eval(Str(3*n-2,3*n-1,3*n)) \\ _M. F. Hasler_, Oct 22 2014
%Y Cf. A030655, A091331.
%K nonn,base,easy
%O 1,1
%A _Charles Duvall_, Oct 08 2014
%E More terms from _Vincenzo Librandi_, Oct 21 2014