A051261 Main diagonal of A018219, i.e., (n, n, a_n) is a winning position.

0, 4, 6, 1, 3, 7, 11, 2, 5, 10, 17, 23, 21, 9, 28, 26, 24, 8, 34, 12, 35, 13, 32, 29, 44, 19, 45, 15, 18, 14, 57, 56, 16, 20, 58, 48, 25, 54, 73, 76, 72, 27, 75, 82, 62, 66, 84, 87, 71, 78, 95, 31, 74, 94, 97, 103, 22, 40, 39, 30, 86, 33, 41, 91, 46, 42, 117, 119, 122, 37

Offset: 0

Author

Michael Kleber

Keywords

• nonn
• nice

Links

• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A018219, Inverse is A077226.

Programs

Mathematica

mex[s_] := Min[Complement[Range[0, Max[{s, -1}] + 1], Flatten[s]]];
f[s_] := Join[s, s + Table[i, {i, Length[s]}]];
T[n_, k_] := T[n, k] = mex[{f[Table[T[n - i, k], {i, n}]], f[Table[T[n, k - i], {i, k}]], f[Table[T[n - i, k - i], {i, Min[n, k]}]]}];
a[n_] := T[n, n];
Table[a[n], {n, 0, 69}] (* Jean-François Alcover, Aug 19 2019, from A018219 Mma code *)

Extensions

Edited and extended by Christian G. Bower, Oct 29 2002