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 A334800 #60 Jul 10 2020 04:23:26
%S A334800 0,0,1,1,2,2,3,4,4,4,4,6,5,7,7,9,6,10,7,11,10,10,8,16,10,12,12,15,9,
%T A334800 17,10,19,14,15,14,23,11,17,16,24,12,25,13,23,22,20,14,34,17,25,20,26,
%U A334800 15,32,20,32,22,23,16,41,17,26,29,36,23,36,18,33,26,36
%N A334800 a(n) is the number of values d*p less than n, where d is a divisor of n, p is a prime, and d*p is not a divisor of n.
%C A334800 F(n) = {d|n, d>=sqrt(n)}. S(d) = {x|x is a prime number<d, not(x | d)} then a(n) = Sum_{F(n)} card(S(d)). - _Devansh Singh_, Jun 16 2020
%C A334800 To say "d*p < n and not(d*p | n)" is equivalent to "p < d' and not(p | d')" where d' = n/d also runs over all divisors, whence the formula. - _M. F. Hasler_, Jun 16 2020
%H A334800 David A. Corneth, <a href="/A334800/b334800.txt">Table of n, a(n) for n = 1..10000</a>
%F A334800 a(n) = A000720(n)-1 = PrimePi(n)-1 when n is a prime number. [Corrected by _M. F. Hasler_]
%F A334800 a(n) = Sum_{d|n} primepi(d)-omega(d), where omega = A001221. - _M. F. Hasler_, Jun 16 2020
%e A334800 a(10)=4 : {3=1*3, 4=2*2, 6=2*3, 7=1*7}, where 1, 2, 5, are excluded because they are divisor of 10; 8 and 9 are excluded because they cannot be written as d*p.
%o A334800 (PARI) a(n) = #select(x->((x<n) && (n%x)), setbinop((x,y)->(x*y), divisors(n), select(x->isprime(x), [1..n]))); \\ _Michel Marcus_, May 13 2020
%o A334800 (PARI) apply( {A334800(n)=sumdiv(n,d,primepi(d)-omega(d))}, [1..99]) \\ _M. F. Hasler_, Jun 16 2020
%Y A334800 Cf. A000720, A001221.
%K A334800 nonn
%O A334800 1,5
%A A334800 _Devansh Singh_, May 12 2020
%E A334800 More terms from _Michel Marcus_, May 13 2020