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A191730
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Dispersion of A047211, (numbers >1 and congruent to 2 or 4 mod 5), by antidiagonals.
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20
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1, 2, 3, 4, 7, 5, 9, 17, 12, 6, 22, 42, 29, 14, 8, 54, 104, 72, 34, 19, 10, 134, 259, 179, 84, 47, 24, 11, 334, 647, 447, 209, 117, 59, 27, 13, 834, 1617, 1117, 522, 292, 147, 67, 32, 15, 2084, 4042, 2792, 1304, 729, 367, 167, 79, 37, 16, 5209, 10104, 6979
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OFFSET
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1,2
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COMMENTS
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For a background discussion of dispersions and their fractal sequences, see A191426. For dispersions of congruence sequences mod 3, mod 4, or mod 5, see A191655, A191663, A191667, A191702.
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Suppose that {2,3,4,5,6} is partitioned as {x1, x2} and {x3,x4,x5}. Let S be the increasing sequence of numbers >1 and congruent to x1 or x2 mod 5, and let T be the increasing sequence of numbers >1 and congruent to x3 or x4 or x5 mod 5. There are 10 sequences in S, each matched by a (nearly) complementary sequence in T. Each of the 20 sequences generates a dispersion, as listed here:
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For further information about these 20 dispersions, see A191722.
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Regarding the dispersions A191722-A191741, there are general formulas for sequences of the type "(a or b mod m)" and "(a or b or c mod m)" used in the relevant Mathematica programs.
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LINKS
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EXAMPLE
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Northwest corner:
1....2....4.....9.....22
3....7....17...42....104
5....12...29...72....179
6....14...34...84....209
8....19...47...117...292
10...24...59...147...367
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MATHEMATICA
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(* Program generates the dispersion array t of the increasing sequence f[n] *)
r = 40; r1 = 12; c = 40; c1 = 12;
a=2; b=4; m[n_]:=If[Mod[n, 2]==0, 1, 0];
f[n_]:=a*m[n+1]+b*m[n]+5*Floor[(n-1)/2]
Table[f[n], {n, 1, 30}] (* A047211 *)
mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1, Length[Union[list]]]
rows = {NestList[f, 1, c]};
Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}];
t[i_, j_] := rows[[i, j]];
TableForm[Table[t[i, j], {i, 1, 10}, {j, 1, 10}]] (* A191730 *)
Flatten[Table[t[k, n - k + 1], {n, 1, c1}, {k, 1, n}]] (* A191730 *)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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