cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A355244 T(w,h)/2 is the minimum slope >= 1/2 that can be chosen as orientation of a w X h rectangle such that the lower bound for the maximum number of covered grid points A354704(w,d) can be achieved by a suitable translation of the rectangle, where T(w,h) and A354704 are triangles read by rows. T(w,h) = -1 if no slope satisfying this condition exists.

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%I A355244 #18 Dec 19 2024 11:56:22
%S A355244 1,1,1,1,2,2,1,3,2,2,1,1,2,2,2,1,1,2,2,2,2,1,6,2,2,2,1,6,2,6,2,2,2,2,
%T A355244 2,2,1,1,2,2,2,1,1,2,1,2,1,2,2,2,2,2,2,2,2,2,1,2,2,2,2,6,2,1,2,2,1,3,
%U A355244 2,-1,2,2,3,2,1,2,-1,3,2,1,2,2,2,2,6,2,1,2,2,1,2
%N A355244 T(w,h)/2 is the minimum slope >= 1/2 that can be chosen as orientation of a w X h rectangle such that the lower bound for the maximum number of covered grid points A354704(w,d) can be achieved by a suitable translation of the rectangle, where T(w,h) and A354704 are triangles read by rows. T(w,h) = -1 if no slope satisfying this condition exists.
%H A355244 Hugo Pfoertner, <a href="/A355244/b355244.txt">Table of n, a(n) for n = 1..210</a>, rows 1..20 of triangle, flattened
%H A355244 Hugo Pfoertner, <a href="/A355244/a355244.pdf">Illustrations of T(4,2) = 3, T(7,6) = T(9,6) = T(13,12) = 1</a>.
%H A355244 Hugo Pfoertner, <a href="/A355244/a355244_1.pdf">Illustrations of T(12,4) = T(12,11) = -1</a>.
%H A355244 Hugo Pfoertner, <a href="/A355244/a355244.gp.txt">PARI program</a>
%e A355244 The triangle begins:
%e A355244     \ h 1  2  3  4  5  6  7  8  9 10 11 12 13
%e A355244    w \ --------------------------------------
%e A355244    1 |  1; |  |  |  |  |  |  |  |  |  |  |  |
%e A355244    2 |  1, 1; |  |  |  |  |  |  |  |  |  |  |
%e A355244    3 |  1, 2, 2; |  |  |  |  |  |  |  |  |  |
%e A355244    4 |  1, 3, 2, 2; |  |  |  |  |  |  |  |  |
%e A355244    5 |  1, 1, 2, 2, 2; |  |  |  |  |  |  |  |
%e A355244    6 |  1, 1, 2, 2, 2, 2; |  |  |  |  |  |  |
%e A355244    7 |  1, 6, 2, 2, 2, 1, 6; |  |  |  |  |  |
%e A355244    8 |  2, 6, 2, 2, 2, 2, 2, 2; |  |  |  |  |
%e A355244    9 |  1, 1, 2, 2, 2, 1, 1, 2, 1; |  |  |  |
%e A355244   10 |  2, 1, 2, 2, 2, 2, 2, 2, 2, 2; |  |  |
%e A355244   11 |  2, 1, 2, 2, 2, 2, 6, 2, 1, 2, 2; |  |
%e A355244   12 |  1, 3, 2,-1, 2, 2, 3, 2, 1, 2,-1, 3; |
%e A355244   13 |  2, 1, 2, 2, 2, 2, 6, 2, 1, 2, 2, 1, 2
%e A355244 .
%e A355244 The first linked illustration shows examples where 2 slopes lead to the same number of covered grid points, where then the smallest multiple of 1/2 is used as a term in the sequence.
%e A355244 The second illustration shows the two examples where it is not possible to cover the maximum number of grid points with a rectangle whose side slope is an integer multiple of 1/2.
%o A355244 (PARI) /* See Pfoertner link. The program can be used to validate the given terms by calling it successively with the slope parameter k, starting with k = 1/2, 2/2=1, 3/2, (4/2 = 2 already covered by 1/2 via symmetry), 5/2, 6/2=3 for the desired rectangle size w X h, until the number of grid points given by A354704(w,k) is reached for the first time as a result. If the slope parameter is not specified, the program attempts to approximate A354704(w,k) and determine a location of the rectangle that maximizes the free margin between the peripheral grid points and the perimeter of the rectangle. */
%Y A355244 Cf. A354704, A354706.
%Y A355244 Cf. A355241 (similar, but with number of covered grid points minimized).
%K A355244 tabl,sign
%O A355244 1,5
%A A355244 _Hugo Pfoertner_, Jun 29 2022