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 A072325 #7 Feb 16 2025 08:32:46
%S A072325 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,2,0,0,0,1,
%T A072325 0,0,0,0,0,0,0,1,0,0,0,1,2,1,1,0,0,0,1,1,1,1,0,0,0,0,1,2,0,0,0,2,2,2,
%U A072325 1,0,0,1,1,1,1,0,1,0,1,1,0,1,0,0,0,0,1,0,0,0,1,1,0,1,0,0,1,0,2,2,2,1,1,0,0
%N A072325 Number of even numbers that cannot be expressed as the difference p-q of two odd primes q < p <= prime(n).
%C A072325 If a(n)=0, then Prime[n], called a cluster prime, is in A038134. If a(n)>0 then Prime[n] is in A038133.
%H A072325 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClusterPrime.html">Cluster Primes</a>
%e A072325 a(25)=1 because Prime[25]=97 and there is 1 even number, 88, that cannot be written as the difference of two odd primes less than or equal to 97.
%t A072325 m=10000; n=PrimePi[m]-1; p=Table[Prime[i+1], {i, n}]; d=Table[0, {m/2}]; c=Table[0, {n}]; For[i=2, i<=n, i++, For[j=1, j<i, j++, diff=p[[i]]-p[[j]]; d[[diff/2]]++ ]; c[[i]]=Count[Take[d, (p[[i]]-3)/2], 0]]; c
%Y A072325 Cf. A038133, A038134.
%K A072325 easy,nonn
%O A072325 2,30
%A A072325 _T. D. Noe_, Jul 15 2002, Nov 19 2006