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A199134 Indices of Greedy Queens (see A065188) below main diagonal. 12
4, 5, 10, 11, 13, 15, 20, 21, 26, 27, 29, 31, 34, 38, 40, 42, 43, 49, 50, 54, 56, 58, 59, 64, 67, 69, 71, 75, 77, 78, 80, 85, 86, 90, 91, 95, 99, 101, 102, 104, 108, 111, 113, 116, 117, 120, 123, 128, 129, 132, 133, 136, 141, 143, 144, 146, 151, 152, 154, 156, 160 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The word "below" in the definition is somewhat ambiguous. More precisely, this is the list of n such that A065188(n) < n. - N. J. A. Sloane, Aug 18 2016

For Greedy Queens that do not attack along antidiagonals, the analogous sequence of indices is A026352.

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..19098

EXAMPLE

Greedy Queens take positions (1,1) (2,3) (3,5) (4,2) (5,4) (6,9) ... and the 4th and 5th are below the main diagonal, so a(1)=4 and a(2)=5.

MATHEMATICA

<<DiscreteMath`Combinatorica`;

base2=Table[{i, j}, {i, 0, 256}, {j, Floor[i/2], 2i}];

base3=DeleteCases[base2, {k_, l_}/; Or[l<-2+Floor[k/GoldenRatio], l>2+Floor[k*GoldenRatio], And[l>3+Floor[k/GoldenRatio], l<Floor[k*GoldenRatio]]], 2 ];

standardQueens=Backtrack[base3, (And[UnsameQ@@ First /@ #, UnsameQ@@ Last/@ #, UnsameQ@@ Subtract@@@ #, UnsameQ@@ Plus@@@ #])&, True&, One];

Position[Subtract@@@ standardQueens, _?Positive]//Flatten

CROSSREFS

Cf. A065188, A026352, A275893 (another version).

A275884 is the complementary sequence.

For runs see A275885, A275886.

Sequence in context: A084750 A092027 A323488 * A131855 A102858 A102857

Adjacent sequences:  A199131 A199132 A199133 * A199135 A199136 A199137

KEYWORD

nonn

AUTHOR

Wouter Meeussen, Nov 04 2011

STATUS

approved

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Last modified August 19 18:30 EDT 2022. Contains 356229 sequences. (Running on oeis4.)