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%I #14 Aug 27 2023 14:37:39
%S 1,2,4,3,6,8,5,10,12,9,7,14,16,15,18,11,20,24,21,30,32,13,22,28,27,36,
%T 40,25,17,26,44,33,42,48,35,50,19,34,52,39,54,56,45,60,72,23,38,64,51,
%U 66,80,55,70,84,63,29,46,68,57,78,88,65,90,96,81,49
%N Triangle T(n, k), n > 0, k = 1..n, read by rows; T(1, 1) = 1, and for n > 1, k = 1..n, T(n, k) is the least unseen multiple of the k-th term of the flattened sequence .
%C In other words, T(n, k) is a multiple of a(k).
%C As a flat sequence, this is a permutation of the positive integers (as each row starts with the least positive integer not yet in the sequence); see A364887 for the inverse permutation.
%H Rémy Sigrist, <a href="/A364884/b364884.txt">Table of n, a(n) for n = 1..10011</a> (rows for n = 1..141 flattened)
%H Rémy Sigrist, <a href="/A364884/a364884.gp.txt">PARI program</a>
%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%e Triangle begins:
%e 1,
%e 2, 4
%e 3, 6, 8
%e 5, 10, 12, 9
%e 7, 14, 16, 15, 18
%e 11, 20, 24, 21, 30, 32
%e 13, 22, 28, 27, 36, 40, 25
%e 17, 26, 44, 33, 42, 48, 35, 50
%e 19, 34, 52, 39, 54, 56, 45, 60, 72
%e 23, 38, 64, 51, 66, 80, 55, 70, 84, 63
%e 29, 46, 68, 57, 78, 88, 65, 90, 96, 81, 49
%e 31, 58, 76, 69, 102, 104, 75, 100, 108, 99, 77, 98
%e ..................................................
%e a(k) 1, 2, 4, 3, 6, 8, 5, 10, 12, 9, 7, 14
%o (PARI) See Links section.
%Y See A361748 and A364885 for similar sequences.
%Y Cf. A364887 (inverse).
%K nonn,tabl
%O 1,2
%A _Rémy Sigrist_, Aug 12 2023
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