A374801 - OEIS

%I #14 Jul 22 2024 14:26:07

%S 1,2,3,5,4,6,13,7,10,12,14,25,11,15,41,8,9,16,21,23,27,31,34,61,22,28,

%T 85,29,36,38,44,59,63,113,37,45,58,64,145,17,20,46,55,57,65,96,101,

%U 181,56,66,221,18,19,40,42,67,78,80,90,94,103,109,117,142,148,265,79,91,313

%N Irregular table T(n, k), n > 0, k = 1..A048691(n), read by rows; the n-th row lists the numbers m such that A003990(m) = n.

%C A003990 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 positive integers with inverse A374802.

%H Rémy Sigrist, <a href="/A374801/b374801.txt">Table of n, a(n) for n = 1..10016</a>

%H Rémy Sigrist, <a href="/A374801/a374801.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    1  1

%e    2  2, 3, 5

%e    3  4, 6, 13

%e    4  7, 10, 12, 14, 25

%e    5  11, 15, 41

%e    6  8, 9, 16, 21, 23, 27, 31, 34, 61

%e    7  22, 28, 85

%e    8  29, 36, 38, 44, 59, 63, 113

%e    9  37, 45, 58, 64, 145

%e   10  17, 20, 46, 55, 57, 65, 96, 101, 181

%e   11  56, 66, 221

%e   12  18, 19, 40, 42, 67, 78, 80, 90, 94, 103, 109, 117, 142, 148, 265

%e   13  79, 91, 313

%e   14  30, 35, 92, 105, 107, 119, 197, 204, 365

%o (PARI) \\ See Links section.

%Y Cf. A003990, A048691, A374802 (inverse).

%K nonn,look,tabf

%O 1,2

%A _Rémy Sigrist_, Jul 20 2024