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a(1)=1 (first row) and then the n-th row of this triangle contains the least set of n unused natural numbers whose sum is a multiple of the sum of the previous row.
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%I #16 Nov 27 2017 02:47:58

%S 1,2,3,4,5,6,7,8,9,21,10,11,12,13,44,14,15,16,17,18,100,19,20,22,23,

%T 24,25,47,26,27,28,29,30,31,32,157,33,34,35,36,37,38,39,40,68,41,42,

%U 43,45,46,48,49,50,51,305,52,53,54,55,56,57,58,59,60,61,155,62,63,64,65,66,67

%N a(1)=1 (first row) and then the n-th row of this triangle contains the least set of n unused natural numbers whose sum is a multiple of the sum of the previous row.

%C The first (n-1) terms of the n-th row contain n-1 smallest natural numbers which have not occurred earlier and the last term is chosen to satisfy the requirement. Permutation A094280 is defined similarly, but the sum of the next row must be greater than that of the current row.

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%e 1;

%e 2, 3;

%e 4, 5, 6;

%e 7, 8, 9, 21;

%e 10, 11, 12, 13, 44;

%e 14, 15, 16, 17, 18, 100;

%Y Inverse: A122154. Cf. A076101, A076102, A076103, A076104.

%K nonn,tabl

%O 1,2

%A _Amarnath Murthy_, Oct 08 2002

%E More terms from _David Wasserman_, Apr 02 2005

%E Description edited by _Antti Karttunen_, Aug 25 2006