cp's OEIS Frontend

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.

A329178 Sum of the products of pairs of Padovan numbers which are two apart, starting from A000931(5).

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%I A329178 #21 Nov 09 2019 10:52:16
%S A329178 1,3,5,11,19,34,62,107,191,335,587,1035,1812,3184,5589,9803,17213,
%T A329178 30199,52999,93014,163214,286439,502655,882095,1547991,2716503,
%U A329178 4767160,8365776,14680889,25763219,45211237,79340227,139232411,244335770,428779502,752455475
%N A329178 Sum of the products of pairs of Padovan numbers which are two apart, starting from A000931(5).
%F A329178 a(n) = Sum_{i=5..n+5} A000931(i)*A000931(i+2).
%F A329178 a(n) = A329227(n+7) - 1.
%F A329178 Conjectures from _Colin Barker_, Nov 09 2019: (Start)
%F A329178 G.f.: (1 + x - x^2 + x^3 - x^4) / ((1 - x)*(1 - 2*x + x^2 - x^3)*(1 + x - x^3)).
%F A329178 a(n) = 2*a(n-1) - 2*a(n-4) + 2*a(n-5) - 2*a(n-6) + a(n-7) for n>6.
%F A329178 (End)
%e A329178 For n=3, a(3) = 1*1 + 1*2 + 1*2 + 2*3 = 11.
%o A329178 (Python)
%o A329178 p = lambda x:[1, 1, 1][x] if x<3 else p(x-2)+p(x-3)
%o A329178 a = lambda x:sum(p(i)*p(i+2) for i in range(x+1))
%Y A329178 Cf. A000931, A133037, A329227.
%K A329178 nonn
%O A329178 0,2
%A A329178 _David Nacin_, Nov 08 2019