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 A261044 #10 Aug 08 2015 15:39:16
%S A261044 0,0,0,0,0,0,0,2,0,5,0,18,0,48,0,170,0,540,0,1868,0,6385,0,22247,0,
%T A261044 79355,0,282754,0,1008714,0,3627599,0,13156851,0,47949883,0,175599692,
%U A261044 0,646384942,0,2392644640,0,8890619925,0,32943781423,0,122928406923,0
%N A261044 Number of solutions to c(1)*prime(4)+...+c(n)*prime(n+3) = -2, where c(i) = +-1 for i > 1, c(1) = 1.
%C A261044 Each second entry is 0 because the terms on the l.h.s. are all odd and the r.h.s. is even.
%F A261044 a(2n-1) = 0 for all n >= 1.
%e A261044 a(8) = 2 counts the two solutions prime(4) - prime(5) + prime(6) - prime(7) - prime(8) + prime(9) - prime(10) + prime(11) = -2 and prime(4) - prime(5) - prime(6) + prime(7) + prime(8) - prime(9) - prime(10) + prime(11) = -2.
%o A261044 (PARI) A261044(n, rhs=-2, firstprime=4)={rhs-=prime(firstprime); my(p=vector(n-1, i, prime(i+firstprime))); sum(i=1, 2^#p-1, sum(j=1, #p, (-1)^bittest(i, j-1)*p[j])==rhs)} \\ For illustrative purpose; too slow for n >> 10.
%Y A261044 Cf. A261061 - A261063 (starting with prime(1), prime(2) and prime(3)), A022894 - A022904, A083309, A022920 (r.h.s. = 0, 1 or 2), A261057, A261059, A261060, A261045 (r.h.s. = -2).
%K A261044 nonn
%O A261044 1,8
%A A261044 _M. F. Hasler_, Aug 08 2015
%E A261044 a(25)-a(49) from _Alois P. Heinz_, Aug 08 2015