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A337655
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a(1)=1; thereafter, a(n) is the smallest number such that both the addition and multiplication tables for (a(1),...,a(n)) contain n*(n+1)/2 different entries (the maximum possible).
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10
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1, 2, 5, 7, 15, 22, 31, 50, 68, 90, 101, 124, 163, 188, 215, 253, 322, 358, 455, 486, 527, 631, 702, 780, 838, 920, 1030, 1062, 1197, 1289, 1420, 1500, 1689, 1765, 1886, 2114, 2353, 2410, 2570, 2686, 2857, 3063, 3207, 3477, 3616, 3845, 3951, 4150, 4480, 4595, 4746, 5030, 5286, 5698, 5999, 6497, 6624, 6938, 7219, 7661, 7838, 8469, 8665, 9198, 9351, 9667, 9966
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OFFSET
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1,2
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COMMENTS
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If one specifies that not only are there n(n+1)/2 distinct numbers in the addition and multiplication tables, but that all n(n+1) numbers are distinct, then the sequence is A337946 - David A. Corneth, Oct 02 2020
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LINKS
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MATHEMATICA
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terms=67; a[1]=b[1]=1; a1=b1={1}; Do[k=a[n-1]+1; While[a2=Union@Join[{2k}, Array[a@#+k&, n-1]]; b2=Union@Join[{k^2}, Array[b@#*k&, n-1]]; Intersection[a2, a1]!={}||Intersection[b2, b1]!={}, k++]; a[n]=b[n]=k; a1=Union[a1, a2]; b1=Union[b1, b2], {n, 2, terms}]; Array[a, terms] (* Giorgos Kalogeropoulos, Nov 15 2021 *)
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PROG
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(C++) See Links section.
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CROSSREFS
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For similar sequences that focus just on the addition or multiplication tables, see A005282 and A066720.
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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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