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 A368822 #3 Jan 07 2024 00:37:02
%S A368822 0,0,0,0,0,1,2,3,4,5,4,3,4,5,4,6,8,8,8,11,10,9,10,12,12,15,14,13,14,
%T A368822 17,16,19,20,19,20,24,22,23,22,23,24,27,24,27,28,27,28,34,32,31,32,35,
%U A368822 34,37,36,37,38,41,38,41,40,41,40,45,44,43,44,49,48,47,48,52,50,53,50,53,52
%N A368822 Number of compositions of n into two non-refactorable parts.
%H A368822 <a href="/index/Com#comp">Index entries for sequences related to compositions</a>
%F A368822 a(n) = Sum_{k=1..n-1} c(k) * c(n-k), where c = A368625.
%e A368822 a(12) = 3 since there are 3 ordered ways to write 12 as the sum of two non-refactorable numbers: 5 + 7 = 6 + 6 = 7 + 5.
%t A368822 Table[Sum[(Ceiling[k/DivisorSigma[0, k]] - Floor[k/DivisorSigma[0, k]]) (Ceiling[(n - k)/DivisorSigma[0, (n - k)]] - Floor[(n - k)/DivisorSigma[0, (n - k)]]), {k, n - 1}], {n, 100}]
%Y A368822 Cf. A159973, A368625.
%K A368822 nonn,easy
%O A368822 1,7
%A A368822 _Wesley Ivan Hurt_, Jan 07 2024