This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A344374 #20 May 31 2021 19:42:41
%S A344374 1,2,2,3,4,5,5,5,7,9,7,9,9,12,10,13,11,17,12,16,15,18,14,17,17,22,19,
%T A344374 24,17,27,18,26,23,29,22,32,24,30,27,31,27,38,28,35,32,38,29,40,31,44,
%U A344374 37,43,32,50,36,44,40,48,36,53,35,50,44,53,42,60,41,58,47,59,45,63,45
%N A344374 a(n) is the number of squarefree numbers appearing in the 1st column of an n X n square array whose elements are the numbers from 1..n^2, listed in increasing order by rows.
%F A344374 a(n) = Sum_{k=1..n} mu(1+n*(k-1))^2, where mu is the Möbius function.
%e A344374 [1 2 3 4 5]
%e A344374 [1 2 3 4] [6 7 8 9 10]
%e A344374 [1 2 3] [5 6 7 8] [11 12 13 14 15]
%e A344374 [1 2] [4 5 6] [9 10 11 12] [16 17 18 19 20]
%e A344374 [1] [3 4] [7 8 9] [13 14 15 16] [21 22 23 24 25]
%e A344374 ------------------------------------------------------------------------
%e A344374 n 1 2 3 4 5
%e A344374 ------------------------------------------------------------------------
%e A344374 a(n) 1 2 2 3 4
%e A344374 ------------------------------------------------------------------------
%e A344374 numbers {1} {1,3} {1,7} {1,5,13} {1,6,11,21}
%e A344374 ------------------------------------------------------------------------
%t A344374 Table[Sum[MoebiusMu[1 + n (k - 1)]^2, {k, n}], {n, 100}]
%Y A344374 Cf. A008683 (mu), A209297.
%K A344374 nonn
%O A344374 1,2
%A A344374 _Wesley Ivan Hurt_, May 17 2021