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 A327247 #18 Jan 14 2024 00:15:23
%S A327247 0,0,1,1,2,2,3,3,4,4,5,5,6,6,6,6,7,7,8,8,8,8,9,9,10,10,11,11,12,12,13,
%T A327247 13,13,13,13,13,14,14,14,14,15,15,16,16,16,16,17,17,18,18,18,18,19,19,
%U A327247 19,19,19,19,20,20,21,21,21,21,21,21,22,22,22,22,23,23,24,24,24
%N A327247 Number of odd prime powers <= n (with exponents > 0).
%F A327247 a(n) = A025528(n) - A000523(n).
%t A327247 Table[Sum[Boole[OddQ[k] && PrimePowerQ[k]], {k, 1, n}], {n, 1, 75}]
%o A327247 (PARI) a(n) = {sum(k=2, primepi(n), logint(n, prime(k)))} \\ _Andrew Howroyd_, Sep 14 2019
%Y A327247 Cf. A000523, A025528, A033270, A061345, A065515, A069637, A085501, A174275 (first differences), A246655, A285879.
%K A327247 nonn
%O A327247 1,5
%A A327247 _Ilya Gutkovskiy_, Sep 14 2019