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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. 4
40, 91, 2743, 6364, 192004, 445423, 13437571, 31173280, 940438000, 2181684211, 65817222463, 152686721524, 4606265134444, 10685888822503, 322372742188651, 747859530853720, 22561485688071160, 52339481270937931, 1578981625422792583, 3663015829434801484 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

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).

FORMULA

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

EXAMPLE

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

MATHEMATICA

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

PROG

(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))

CROSSREFS

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

Sequence in context: A044559 A092613 A005930 * A036194 A023695 A038466

Adjacent sequences:  A261930 A261931 A261932 * A261934 A261935 A261936

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Sep 06 2015

STATUS

approved

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Last modified December 1 15:57 EST 2021. Contains 349430 sequences. (Running on oeis4.)