cp's OEIS Frontend

A270708 a(n) = A048739(n-1) mod A000129(floor(n/2)).

%I A270708 #12 Mar 29 2016 23:40:18
%S A270708 0,0,0,1,4,3,0,1,28,27,0,1,168,167,0,1,984,983,0,1,5740,5739,0,1,
%T A270708 33460,33459,0,1,195024,195023,0,1,1136688,1136687,0,1,6625108,
%U A270708 6625107,0,1,38613964,38613963,0,1,225058680,225058679,0,1,1311738120,1311738119,0,1,7645370044,7645370043,0,1
%N A270708 a(n) = A048739(n-1) mod A000129(floor(n/2)).
%C A270708 It appears that a(4*n+1) = 1. - _Michel Marcus_, Mar 23 2016
%F A270708 Empirical g.f.: x^5*(1+3*x-6*x^4+6*x^5+x^8-x^9) / ((1-x)*(1+x^2)*(1+2*x^2-x^4)*(1-2*x^2-x^4)). - _Colin Barker_, Mar 22 2016
%e A270708 a(7) = 3 because a(7) = A048739(6) mod A000129(floor(7/2)) = (1 + 2 + 5 + 12 + 29 + 70 + 169) mod 5 = 288 mod 5 = 3.
%e A270708 a(8) = 0 because a(8) = A048739(7) mod A000129(floor(8/2)) = (1 + 2 + 5 + 12 + 29 + 70 + 169 + 408) mod 12 = 0.
%e A270708 a(9) = 1 because a(9) = A048739(8) mod A000129(floor(9/2)) = (1 + 2 + 5 + 12 + 29 + 70 + 169 + 408 + 985) mod 12 = 1.
%o A270708 (PARI) a000129(n) = ([2, 1; 1, 0]^n)[2, 1];
%o A270708 for(n=2, 1e2, print1(sum(k=1, n, a000129(k)) % a000129(n\2),", "));
%Y A270708 Cf. A000129 (Pell numbers), A048739 (partial sums of Pell numbers).
%K A270708 nonn
%O A270708 2,5
%A A270708 _Altug Alkan_, Mar 22 2016