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A201208 One 1, two 2's, three 1's, four 2's, five 1's, ... 2

%I

%S 1,2,2,1,1,1,2,2,2,2,1,1,1,1,1,2,2,2,2,2,2,1,1,1,1,1,1,1,2,2,2,2,2,2,

%T 2,2,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,2,2,

%U 2,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2

%N One 1, two 2's, three 1's, four 2's, five 1's, ...

%F a(n)=A057212 + 1 (T. D. Noe, Nov 28 2011)

%e May be written as a triangle:

%e 1

%e 2 2

%e 1 1 1

%e 2 2 2 2

%e 1 1 1 1 1

%e 2 2 2 2 2 2

%e 1 1 1 1 1 1 1

%e Row sums are A022998(n+1).

%t ReplaceAll[ColumnForm[Table[Mod[k, 2], {k, 12}, {n, k}], Center], 0 -> 2] (* _Alonso del Arte_, Nov 28 2011 *)

%o (Haskell)

%o a201208 n = a201208_list !! (n-1)

%o a201208_list = concat $ zipWith ($) (map replicate [1..]) a000034_list

%o -- _Reinhard Zumkeller_, Dec 02 2011

%Y Cf. A057212, A022998.

%Y Cf. A000034.

%K nonn,tabl,easy

%O 1,2

%A _Paul Curtz_, Nov 28 2011

%E Edited by _N. J. A. Sloane_, Dec 02 2011

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Last modified August 20 12:43 EDT 2014. Contains 245798 sequences.