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 A140102 Term-by-term differences of A140101 and A140100; also, equals the complement of A140103, which is the term-by-term sums of A140101 and A140100, where A140101 is the complement of A140100. 15
 0, 1, 2, 4, 5, 6, 7, 9, 10, 11, 13, 14, 15, 16, 18, 19, 21, 22, 23, 24, 26, 27, 28, 30, 31, 32, 33, 35, 36, 37, 38, 40, 41, 42, 44, 45, 46, 47, 49, 50, 52, 53, 54, 55, 57, 58, 59, 61, 62, 63, 64, 66, 67, 68, 70, 71, 72, 73, 75, 76, 78, 79, 80, 81, 83, 84, 85, 87, 88, 89, 90, 92, 93 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS N. J. A. Sloane, Table of n, a(n) for n = 0..50000, Sep 13 2016 (First 1001 terms from Reinhard Zumkeller) F. Michel Dekking, Jeffrey Shallit, and N. J. A. Sloane, Queens in exile: non-attacking queens on infinite chess boards, Electronic J. Combin., 27:1 (2020), #P1.52. N. J. A. Sloane, Maple program for A140100, A140101, A140102, A140103 FORMULA a(n) = A140101(n) - A140100(n). Theorem: the limit of A140103(n)/A140102(n) = t^2 = 3.38297576... where the limit of A140101(n)/A140100(n) = t = 1.839286755... and t = tribonacci constant satisfies: t^3 = 1 + t + t^2. MAPLE See link. MATHEMATICA nmax = 100; y[0] = 0; x[1] = 1; y[1] = 2; x[n_] := x[n] = For[yn = y[n-1] + 1, True, yn++, For[xn = x[n-1] + 1, xn < yn, xn++, xx = Array[x, n-1]; yy = Array[y, n-1]; If[FreeQ[xx, xn | yn] && FreeQ[yy, xn | yn] && FreeQ[yy - xx, yn - xn] && FreeQ[yy + xx, yn - xn], y[n] = yn; Return[xn]]]]; Do[x[n], {n, 1, nmax}]; Join[{0}, yy - xx] (* Jean-François Alcover, Aug 01 2018 *) PROG (PARI) {X=[1]; Y=[2]; D=[1]; S=[3]; print1(Y[1]-X[1]", "); for(n=1, 100, for(j=2, 2*n, if(setsearch(Set(concat(X, Y)), j)==0, Xt=concat(X, j); for(k=j+1, 3*n, if(setsearch(Set(concat(Xt, Y)), k)==0, if(setsearch(Set(concat(D, S)), k-j)==0, if(setsearch(Set(concat(D, S)), k+j)==0, X=Xt; Y=concat(Y, k); D=concat(D, k-j); S=concat(S, k+j); print1(Y[ #X]-X[ #Y]", "); break); break))))))} CROSSREFS Cf. A140103 (complement); A140100, A140101; A058265. For first differences of A140100, A140101, A140102, A140103 see A305392, A305374, A305393, A305394. Sequence in context: A023733 A154112 A039101 * A288866 A084437 A037083 Adjacent sequences:  A140099 A140100 A140101 * A140103 A140104 A140105 KEYWORD nonn AUTHOR Paul D. Hanna, Jun 04 2008 EXTENSIONS Terms computed by Reinhard Zumkeller. Offset and initial term changed by N. J. A. Sloane, Oct 10 2016 STATUS approved

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Last modified September 20 17:04 EDT 2020. Contains 337265 sequences. (Running on oeis4.)