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 A305700 #16 Apr 29 2019 05:41:26
%S A305700 0,0,1,3,5,19,19,17,89,673,47,979,1297,4883,1771,79613,31,393959,2033,
%T A305700 85639,116551,616181,4111,16637083,727403,13117673,72631,122771983,
%U A305700 194803,31691158757,491951,124085749,9079549,114103102711,92671,743246297281,213649,197986199,972486919,144015774883
%N A305700 a(n) is the numerator of Sum_{primes p < n} 1/(n-p).
%H A305700 Robert Israel, <a href="/A305700/b305700.txt">Table of n, a(n) for n = 1..3569</a>
%H A305700 Math Overflow, <a href="https://mathoverflow.net/questions/302351/sum-of-reciprocals-of-integers-minus-primes">Sum of reciprocals of integers minus primes</a>.
%e A305700 Sum_{primes p < 6} 1/(6-p) = 1/(6-2) + 1/(6-3) + 1/(6-5) = 19/12 so a(6) = 19.
%p A305700 N:= 100: # to get a(1)..a(N)
%p A305700 P:= select(isprime, [2,seq(i,i=3..N,2)]):
%p A305700 seq(numer(add(1/(n-p),p=select(`<`,P,n))), n=1..N);
%t A305700 a[n_] := Sum[1/(n-p), {p, Prime[Range[PrimePi[n-1]]]}] // Numerator;
%t A305700 Array[a, 100] (* _Jean-François Alcover_, Apr 29 2019 *)
%o A305700 (PARI) a(n) = my(p=select(x->isprime(x), [1..n-1])); numerator(sum(k=1, #p, 1/(n-p[k]))); \\ _Michel Marcus_, Jun 09 2018
%Y A305700 Cf. A305702 (denominators).
%K A305700 nonn,frac
%O A305700 1,4
%A A305700 _Robert Israel_, Jun 08 2018