A081693 Define two sequences by A_n = mex{A_i,B_i : 0 <= i < n}, B_n = B_{n-1} + (A_n-A_{n-1})(A_n-A_{n-1}+1), where the mex of a set is the smallest nonnegative integer not in the set. Sequence gives B_n. A_n is in A081692.

0, 2, 8, 10, 12, 14, 16, 22, 28, 34, 40, 46, 48, 50, 52, 54, 60, 62, 64, 66, 68, 74, 76, 78, 80, 82, 88, 90, 92, 94, 96, 102, 104, 106, 108, 110, 116, 122, 128, 134, 140, 142, 144, 146, 148, 154, 160, 166, 172, 178, 180, 182, 184, 186, 192, 198, 204, 210, 216, 218

Offset: 0

Author

N. J. A. Sloane, Apr 02 2003

Keywords

• nonn

Comments

Conjecture: Except for the initial 0, this is the sequence of positions of 1 in the fixed point of the morphism 0->01, 1->0000; see A284683. - Clark Kimberling, Apr 13 2017

Links

• A. S. Fraenkel, Home Page
• A. S. Fraenkel, New games related to old and new sequences, INTEGERS, Electronic J. of Combinatorial Number Theory, Vol. 4, Paper G6, 2004.

Crossrefs

Apart from initial terms, complement of A081692. Cf. A081691.

Programs

Mathematica

mex[{}]=0; mex[s_] := Complement[Range[0, 1+Max@@s], s][[1]]; A[0]=B[0]=0; A[n_] := A[n]=mex[Flatten[Table[{A[i], B[i]}, {i, 0, n-1}]]]; B[n_] := B[n]=B[n-1]+(A[n]-A[n-1])*(A[n]-A[n-1]+1); a := B

Extensions

More terms from Vladeta Jovovic, Apr 04 2003