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 A201250 #28 Oct 06 2024 13:09:53
%S A201250 1,3,8,16,36,38,70,108,116,148,251,280,1964
%N A201250 Integers k such that Sum_{i=1..k-1} (-1)^(i+1)*primepi((k-i+1)^2) = Sum_{i=1..k-1} (-1)^(i+1)*primepi((k-i)^2).
%F A201250 A_n = Sum_{i=1..n-1} (-1)^i * pi((n-i+1)^2);
%F A201250 B_n = Sum_{i=1..n-1} (-1)^i * pi((n-i)^2);
%F A201250 Sequence is S_n = {index(A_n - B_n) such that A_n - B_n = 0}.
%e A201250 For k = 3, pi(3^2)-pi(2^2) = 2 = pi(2^2)-pi(1^2), so 3 is a term.
%o A201250 (PARI) isok(k) = sum(i=1, k-1, (-1)^(i+1)*primepi((k-i+1)^2)) == sum(i=1, k-1, (-1)^(i+1)*primepi((k-i)^2)); \\ _Michel Marcus_, Aug 16 2022
%Y A201250 Cf. A000720.
%K A201250 nonn,more
%O A201250 1,2
%A A201250 _Daniel Tisdale_, Nov 28 2011
%E A201250 New name and a(13) from _Michel Marcus_, Aug 16 2022