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A077341 Triangle in which n-th row contains the first n numbers, not already present, that begin with n. 5

%I

%S 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,

%T 73,74,75,8,80,81,82,83,84,85,86,9,90,91,92,93,94,95,96,97,10,100,101,

%U 102,103,104,105,106,107,108,11,110,111,112,113,114,115,116,117,118,119,12

%N Triangle in which n-th row contains the first n numbers, not already present, that begin with n.

%C 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.

%C The first term of the 20th row is 200 unlike the 20th row of A077339 where it is 20.

%H M. F. Hasler, <a href="/A077341/b077341.txt">Table of n, a(n) for n = 1..5350</a>

%e Triangle begins:

%e 1

%e 2 20

%e 3 30 31

%e 4 40 41 42

%e 5 50 51 52 53

%e ...

%o (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

%Y Cf. A077339, A077340 (see there for differences), A077342, A077343.

%K base,easy,nonn,tabl

%O 1,2

%A _Amarnath Murthy_, Nov 05 2002

%E Edited by _N. J. A. Sloane_, Jun 12 2007

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Last modified October 16 09:02 EDT 2021. Contains 348041 sequences. (Running on oeis4.)