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Irregular triangle T(n, k), n >= 0, k = 1..A120880(n), read by rows; the n-th lists the integers m such that A374560(m) = n.
3

%I #18 Jul 22 2024 11:23:12

%S 0,1,2,4,3,5,6,7,8,9,11,13,12,17,18,24,10,14,15,16,19,20,22,26,21,23,

%T 25,27,28,29,30,31,32,33,34,35,37,39,41,43,38,42,47,48,51,52,58,62,40,

%U 49,50,60,59,61,70,71,72,73,83,85,84,97,98,112,36,44,45,46,53,54

%N Irregular triangle T(n, k), n >= 0, k = 1..A120880(n), read by rows; the n-th lists the integers m such that A374560(m) = n.

%C A374560 corresponds to a square array, but we consider it here as a flat sequence (when its values are read according along its antidiagonals).

%C As a flat sequence, this is a permutation of the nonnegative integers with inverse A374792.

%H Rémy Sigrist, <a href="/A374791/b374791.txt">Table of n, a(n) for n = 0..8255</a>

%H Rémy Sigrist, <a href="/A374791/a374791.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 T(n, k) begins:

%e n n-th row

%e -- ------------------------------

%e 0 0

%e 1 1, 2

%e 2 4

%e 3 3, 5

%e 4 6, 7, 8, 9

%e 5 11, 13

%e 6 12

%e 7 17, 18

%e 8 24

%e 9 10, 14

%e 10 15, 16, 19, 20

%e 11 22, 26

%e 12 21, 23, 25, 27

%e 13 28, 29, 30, 31, 32, 33, 34, 35

%e 14 37, 39, 41, 43

%e 15 38, 42

%o (PARI) \\ See Links section.

%Y Cf. A120880, A374560, A374792 (inverse).

%K nonn,tabl,base

%O 0,3

%A _Rémy Sigrist_, Jul 20 2024