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 A079326 a(n) = the largest number m such that if m monominoes are removed from an n X n square then an L-tromino must remain. 19
 1, 2, 7, 9, 17, 20, 31, 35, 49, 54, 71, 77, 97, 104, 127, 135, 161, 170, 199, 209, 241, 252, 287, 299, 337, 350, 391, 405, 449, 464, 511, 527, 577, 594, 647, 665, 721, 740, 799, 819, 881, 902, 967, 989, 1057, 1080, 1151, 1175, 1249, 1274, 1351, 1377, 1457 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 LINKS Table of n, a(n) for n=2..54. Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1). FORMULA a(n) = (n^2)/2 - 1 (n even), (n^2-n)/2 - 1 (n odd). a(n) = A204557(n-1) / (n-1). - Reinhard Zumkeller, Jan 18 2012 From Bruno Berselli, Jan 18 2011: (Start) G.f.: x^2*(1+x+3*x^2-x^4)/((1+x)^2*(1-x)^3). a(n) = n*(2*n+(-1)^n-1)/4 - 1. a(n) = A105638(-n+2). (End) EXAMPLE a(3)=2 because if a middle row of 3 monominoes are removed from the 3 X 3, no L remains. MATHEMATICA Table[FrobeniusNumber[{a, a + 1, a + 2}], {a, 2, 54}] (* Zak Seidov, Jan 08 2015 *) CROSSREFS Frobenius number for k successive numbers: A028387 (k=2), this sequence (k=3), A138984 (k=4), A138985 (k=5), A138986 (k=6), A138987 (k=7), A138988 (k=8). Cf. A093353, A104519. Sequence in context: A042807 A005988 A199537 * A055673 A177737 A336770 Adjacent sequences: A079323 A079324 A079325 * A079327 A079328 A079329 KEYWORD nonn,easy AUTHOR Mambetov Timur (timur_teufel(AT)mail.ru), Feb 13 2003 EXTENSIONS Edited by Don Reble, May 28 2007 STATUS approved

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Last modified September 15 11:45 EDT 2024. Contains 375938 sequences. (Running on oeis4.)