cp's OEIS Frontend

A261995 The first of four consecutive positive integers the sum of the squares of which is equal to the sum of the squares of twenty-one consecutive positive integers.

%I A261995 #6 Sep 08 2015 08:54:00
%S A261995 42,123,315,1827,4659,13650,34794,201114,512610,1501539,3827187,
%T A261995 22120875,56382603,165155802,420955938,2433095298,6201573882,
%U A261995 18165636843,46301326155,267618362067,682116744579,1998054897090,5092724921274,29435586732234,75026640329970
%N A261995 The first of four consecutive positive integers the sum of the squares of which is equal to the sum of the squares of twenty-one consecutive positive integers.
%C A261995 For the first of the corresponding twenty-one consecutive positive integers, see A261996.
%H A261995 Colin Barker, <a href="/A261995/b261995.txt">Table of n, a(n) for n = 1..1000</a>
%H A261995 <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 A261995 G.f.: -3*x*(6*x^8+8*x^6+27*x^5-596*x^4+504*x^3+64*x^2+27*x+14) / ((x-1)*(x^8-110*x^4+1)).
%e A261995 42 is in the sequence because 42^2 + ... + 45^2 = 7574 = 8^2 + ... + 28^2.
%o A261995 (PARI) Vec(-3*x*(6*x^8+8*x^6+27*x^5-596*x^4+504*x^3+64*x^2+27*x+14)/((x-1)*(x^8-110*x^4+1)) + O(x^40))
%Y A261995 Cf. A157092, A246642, A261996.
%K A261995 nonn,easy
%O A261995 1,1
%A A261995 _Colin Barker_, Sep 08 2015