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 A237990 #19 Jun 24 2024 08:47:42 %S A237990 4,8,16,20,40,44,56,64,72,80,92,96,108,116,120,124,132,136,140,144, %T A237990 148,152,156,164,176,184,188,196,200,204,208,224,232,240,252,256,264, %U A237990 268,272 %N A237990 Numbers m such that the numbers of primes, even positive integers and odd positive integers less than or equal to m are all even. %C A237990 A subsequence of A008586. %H A237990 Ivan N. Ianakiev, <a href="/A237990/b237990.txt">Table of n, a(n) for n = 1..10000</a> %F A237990 a(n) == 0 (mod 4) %e A237990 A tetrahedral die whose faces are marked with the numbers from 1 to 4 has an even number of sides marked with prime numbers, even integers and odd integers. Therefore, 4 is in the sequence. %t A237990 Select[Range[4, 1000, 4], EvenQ[PrimePi[#]] &] (* _Paolo Xausa_, Jun 24 2024 *) %Y A237990 Cf. A008586, A237989. %K A237990 nonn,easy %O A237990 1,1 %A A237990 _Ivan N. Ianakiev_, Feb 16 2014