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A077341
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Triangle in which n-th row contains the first n numbers, not already present, that begin with n.
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5
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1, 2, 20, 3, 30, 31, 4, 40, 41, 42, 5, 50, 51, 52, 53, 6, 60, 61, 62, 63, 64, 7, 70, 71, 72, 73, 74, 75, 8, 80, 81, 82, 83, 84, 85, 86, 9, 90, 91, 92, 93, 94, 95, 96, 97, 10, 100, 101, 102, 103, 104, 105, 106, 107, 108, 11, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 12
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Every positive number appears exactly once. Proof: N will appear as the first term of row N, unless it has already appeared. And no term is repeated, by definition.
The first term of the 20th row is 200 unlike the 20th row of A077339 where it is 20.
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LINKS
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EXAMPLE
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Triangle begins:
1
2 20
3 30 31
4 40 41 42
5 50 51 52 53
...
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PROG
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(PARI) {u=[]; for(m=1, 19, o=0; for(n=1, m, while(setsearch(u, a=A077339(m, n+o)), o++); u=setunion(u, Set(a)); print1(a", ")))} \\ M. F. Hasler, Jan 08 2013
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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