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 A228430 #12 Mar 30 2014 19:32:21 %S A228430 0,1,1,2,2,0,2,3,2,3,2,3,4,1,2,1,4,3,1,1,6,4,2,4,4,4,1,5,3,5,6,4,6,3, %T A228430 5,5,6,3,3,5,5,5,9,3,3,11,6,7,4,8,7,12,7,5,10,4,3,8,8,3,11,6,5,10,4,6, %U A228430 14,6,3,9,3,12,12,9,3,11,6,10,15,7,7,8,3,6,11,8,11,10,7,3,11,10,7,11,4,6,13,11,9,8 %N A228430 Number of ways to write n = x + y (x, y > 0) with x^4 + y*(y+1)/2 prime. %C A228430 Conjecture: (i) a(n) > 0 except for n = 1, 6. %C A228430 (ii) For any positive integer n not among 1, 3, 14, 25, there are positive integers x and y with x + y = n such that x^3 + y*(y+1)/2 is prime. %H A228430 Zhi-Wei Sun, <a href="/A228430/b228430.txt">Table of n, a(n) for n = 1..10000</a> %e A228430 a(14) = 1 since 14 = 4 + 10 with 4^4 + 10*11/2 = 311 prime. %e A228430 a(27) = 1 since 27 = 22 + 5 with 22^4 + 5*6/2 = 234271 prime. %t A228430 a[n_]:=Sum[If[PrimeQ[x^4+(n-x)(n-x+1)/2],1,0],{x,1,n-1}] %t A228430 Table[a[n],{n,1,100}] %Y A228430 Cf. A000040, A000217, A000583, A228425, A228428, A228429. %K A228430 nonn %O A228430 1,4 %A A228430 _Zhi-Wei Sun_, Nov 10 2013