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A261932 The first of two consecutive positive integers the sum of the squares of which is equal to the sum of the squares of ten consecutive positive integers. 4
26, 48, 68, 126, 468, 866, 1226, 2268, 8406, 15548, 22008, 40706, 150848, 279006, 394926, 730448, 2706866, 5006568, 7086668, 13107366, 48572748, 89839226, 127165106, 235202148, 871602606, 1612099508, 2281885248, 4220531306, 15640274168, 28927951926 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the first of the corresponding ten consecutive positive integers, see A261934.

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,18,-18,0,0,-1,1).

FORMULA

G.f.: -2*x*(4*x^8-x^7+x^5-63*x^4+29*x^3+10*x^2+11*x+13) / ((x-1)*(x^4-4*x^2-1)*(x^4+4*x^2-1)).

a(n) = a(n-1) + 18*a(n-4) - 18*a(n-5) - a(n-8) + a(n-9) for n>8. - Vincenzo Librandi, Sep 07 2015

EXAMPLE

26 is in the sequence because 26^2 + 27^2 = 7^2 + 8^2 + ... + 16^2.

MATHEMATICA

CoefficientList[Series[2 (4 x^8 - x^7 + x^5 - 63 x^4 + 29 x^3 + 10 x^2 + 11 x + 13)/((1 - x) (x^4 - 4 x^2 - 1) (x^4 + 4 x^2 - 1)), {x, 0, 45}], x] (* Vincenzo Librandi, Sep 07 2015 *)

PROG

(PARI) Vec(-2*x*(4*x^8-x^7+x^5-63*x^4+29*x^3+10*x^2+11*x+13)/((x-1)*(x^4-4*x^2-1)*(x^4+4*x^2-1)) + O(x^40))

CROSSREFS

Cf. A001652, A031138, A261933, A261934, A261935.

Sequence in context: A159651 A118367 A316120 * A324041 A137263 A073249

Adjacent sequences:  A261929 A261930 A261931 * A261933 A261934 A261935

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Sep 06 2015

STATUS

approved

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Last modified December 6 20:22 EST 2021. Contains 349567 sequences. (Running on oeis4.)