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A120913 Triangle read by rows where t(n,m) is the (ceiling(n/m))th integer from among those positive integers not occurring earlier in the sequence. 1

%I

%S 1,3,2,6,5,4,10,8,9,7,15,13,12,14,11,21,18,17,19,20,16,28,25,24,23,26,

%T 27,22,36,32,31,30,33,34,35,29,45,41,39,40,38,42,43,44,37,55,50,49,48,

%U 47,51,52,53,54,46,66,61,59,58,60,57,62,63,64,65,56,78,72,70,69,71,68

%N Triangle read by rows where t(n,m) is the (ceiling(n/m))th integer from among those positive integers not occurring earlier in the sequence.

%C This is a self-inverse permutation of the positive integers. For fixed n, U(n,k) as defined above is a permution of 1..n. - _Franklin T. Adams-Watters_, Jul 25 2006

%F T(n,k) = n(n-1)/2 + U(n,k), where U(n,k) = ceiling(n/k) if ceiling(n/ceiling(n/k)) = k, otherwise U(n,k) = k. - _Franklin T. Adams-Watters_, Jul 25 2006

%Y Cf. A120911.

%K easy,nonn,tabl

%O 1,2

%A _Leroy Quet_, Jul 15 2006

%E More terms from _Franklin T. Adams-Watters_, Jul 25 2006

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Last modified October 26 02:14 EDT 2021. Contains 348256 sequences. (Running on oeis4.)