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 A291708 #16 Dec 19 2017 02:29:49 %S A291708 0,1,0,1,2,1,2,2,2,4,1,3,3,4,3,6,2,6,4,6,4,8,3,9,5,9,4,9,5,11,7,9,7, %T A291708 13,6,15,7,10,9,14,8,16,10,14,10,16,9,19,11,18,10,17,11,21,13,18,12, %U A291708 20,13,25,15,18,15,24,14,27,15,19,17,26,16,28,18,25 %N A291708 Number of partitions of n into two prime parts or two nonprime parts. %H A291708 <a href="/index/Par#part">Index entries for sequences related to partitions</a> %F A291708 a(n) = Sum_{i=1..floor(n/2)} [A010051(i) = A010051(n-i)], where [] is the Iverson bracket. %F A291708 a(n) = floor(n/2) - A062602(n). %t A291708 Table[Sum[KroneckerDelta[(PrimePi[k] - PrimePi[k - 1]), (PrimePi[n - k] - PrimePi[n - 1 - k])], {k, Floor[n/2]}], {n, 80}] %Y A291708 Cf. A010051, A062602. %K A291708 nonn,easy %O A291708 1,5 %A A291708 _Wesley Ivan Hurt_, Oct 20 2017