A261933 The first of two consecutive positive integers the sum of the squares of which is equal to the sum of the squares of seventeen consecutive positive integers.

40, 91, 2743, 6364, 192004, 445423, 13437571, 31173280, 940438000, 2181684211, 65817222463, 152686721524, 4606265134444, 10685888822503, 322372742188651, 747859530853720, 22561485688071160, 52339481270937931, 1578981625422792583, 3663015829434801484

Offset: 1

Author

Colin Barker, Sep 06 2015

Keywords

• nonn
• easy

Comments

For the first of the corresponding seventeen consecutive positive integers, see A261935.

Examples

			40 is in the sequence because 40^2 + 41^2 = 5^2 + 6^2 + ... + 21^2.
		

Links

• Colin Barker, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (1,70,-70,-1,1).

Crossrefs

Cf. A001652, A031138, A261932, A261934, A261935.

Programs

Mathematica

LinearRecurrence[{1,70,-70,-1,1},{40,91,2743,6364,192004},20] (* Harvey P. Dale, Oct 17 2015 *)

PARI

Vec(-x*(40*x^4+51*x^3-148*x^2+51*x+40)/((x-1)*(x^4-70*x^2+1)) + O(x^40))

Formula

G.f.: -x*(40*x^4+51*x^3-148*x^2+51*x+40) / ((x-1)*(x^4-70*x^2+1)).