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 A316776 #14 Jul 31 2018 22:47:56
%S A316776 0,0,0,1,2,1,1,3,2,2,3,3,3,2,3,2,4,5,1,4,4,3,3,5,5,4,5,4,4,6,2,5,7,2,
%T A316776 6,6,4,5,8,4,4,8,5,5,9,5,5,8,3,6,8,5,5,8,6,8,10,7,5,13,4,6,10,3,8,9,6,
%U A316776 5,8,7,8,12,6,5,12,4,8,12,4,9,11,5,5,13,10,6,11,7,7,14,6,9,14,6,8,11
%N A316776 a(n) is the number of integers 0 < k < n such that n^2 - k^2 is a semiprime.
%e A316776 a(11) = 3 because 11^2 - 6^2 = 85, 11^2 - 8^2 = 57 and 11^2 - 10^2 = 21 are the only three semiprimes of the form 11^2 - k^2 with 0 < k < 11.
%t A316776 a[n_] := Sum[Boole[ PrimeOmega[n^2 - k^2] == 2], {k, n-1}]; Array[a, 96] (* _Giovanni Resta_, Jul 13 2018 *)
%o A316776 (PARI) a(n) = sum(k=1, n-1, bigomega(n^2-k^2)==2); \\ _Michel Marcus_, Jul 12 2018
%Y A316776 Cf. A001358.
%K A316776 nonn
%O A316776 1,5
%A A316776 _Arnauld Chevallier_, Jul 12 2018