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A230548
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Twin hearts patterns packing into n X n coins.
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6
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0, 1, 2, 3, 6, 7, 8, 12, 15, 16, 24, 25, 28, 35, 40, 41, 54, 55, 60, 70, 77, 78, 96, 97, 104, 117, 126, 127, 150, 151, 160, 176, 187, 188, 216, 217, 228, 247, 260, 261, 294, 295, 308, 330, 345, 346, 384, 385, 400, 425, 442
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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2,3
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COMMENTS
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Twin hearts (6c4a type) is one of total 17 distinct patterns appearing in 3X2 coins where each pattern consists of 6 perimeter parts from each coin and forms a continuous area.
a(n) is the number of total twin hearts patterns (6c4a type: 6-curves cover 4 coins) packing into n X n coins with rotation not allowed. The total coins left after packing twin hearts patterns into n X n coins is A230549 and voids left is A230550. See illustration in links.
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LINKS
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FORMULA
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G.f.: x^2 * (x^10 + x^8 + 2*x^5 + 3*x^4 + 2*x^3 + 2*x^2 + x)/((1+x^3) * (1-x^3)^2 * (1-x^2)) (conjectured). - Ralf Stephan, Oct 30 2013
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PROG
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(Small Basic)
col = 1
row = 0
For n = 2 To 100
add = 0
If Math.Remainder(n, 2) * Math.Remainder(n, 3) <> 0 Then
add = 1
EndIf
If n >= 4 And Math.Remainder(n, 2) = 0 Then
col = col + 1
EndIf
If n >= 3 And Math.Remainder(n, 3) = 0 Then
row = row + 1
EndIf
T = col * row + add
TextWindow.Write(T+", ")
EndFor
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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