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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 (list; table; graph; refs; listen; history; text; internal format)
 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 M. F. Hasler, Table of n, a(n) for n = 1..5350 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 Adjacent sequences:  A077338 A077339 A077340 * A077342 A077343 A077344 KEYWORD base,easy,nonn,tabl AUTHOR Amarnath Murthy, Nov 05 2002 EXTENSIONS Edited by N. J. A. Sloane, Jun 12 2007 STATUS approved

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Last modified September 20 13:56 EDT 2021. Contains 347586 sequences. (Running on oeis4.)