cp's OEIS Frontend

A261996 The first of twenty-one consecutive positive integers the sum of the squares of which is equal to the sum of the squares of four consecutive positive integers.

%I A261996 #5 Sep 08 2015 08:54:09
%S A261996 8,44,128,788,2024,5948,15176,87764,223712,655316,1670312,9654332,
%T A261996 24607376,72079892,183720224,1061889836,2706588728,7928133884,
%U A261996 20207555408,116798228708,297700153784,872022648428,2222647375736,12846743269124,32744310328592
%N A261996 The first of twenty-one consecutive positive integers the sum of the squares of which is equal to the sum of the squares of four consecutive positive integers.
%C A261996 For the first of the corresponding four consecutive positive integers, see A261995.
%H A261996 Colin Barker, <a href="/A261996/b261996.txt">Table of n, a(n) for n = 1..1000</a>
%H A261996 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,110,-110,0,0,-1,1).
%F A261996 G.f.: 4*x*(x^8+3*x^7+3*x^6+9*x^5-89*x^4-165*x^3-21*x^2-9*x-2) / ((x-1)*(x^8-110*x^4+1)).
%e A261996 8 is in the sequence because 8^2 + ... + 28^2 = 7574 = 42^2 + ... + 45^2.
%o A261996 (PARI) Vec(4*x*(x^8+3*x^7+3*x^6+9*x^5-89*x^4-165*x^3-21*x^2-9*x-2)/((x-1)*(x^8-110*x^4+1)) + O(x^40))
%Y A261996 Cf. A157092, A246642, A261995.
%K A261996 nonn,easy
%O A261996 1,1
%A A261996 _Colin Barker_, Sep 08 2015