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A077341
Triangle in which n-th row contains the first n numbers, not already present, that begin with n.
5
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
OFFSET
1,2
COMMENTS
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.
LINKS
EXAMPLE
Triangle begins:
1
2 20
3 30 31
4 40 41 42
5 50 51 52 53
...
PROG
(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
CROSSREFS
Cf. A077339, A077340 (see there for differences), A077342, A077343.
Sequence in context: A082259 A342077 A077339 * A344545 A076495 A308387
KEYWORD
base,easy,nonn,tabl
AUTHOR
Amarnath Murthy, Nov 05 2002
EXTENSIONS
Edited by N. J. A. Sloane, Jun 12 2007
STATUS
approved