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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. 2
8, 44, 128, 788, 2024, 5948, 15176, 87764, 223712, 655316, 1670312, 9654332, 24607376, 72079892, 183720224, 1061889836, 2706588728, 7928133884, 20207555408, 116798228708, 297700153784, 872022648428, 2222647375736, 12846743269124, 32744310328592 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the first of the corresponding four consecutive positive integers, see A261995.

LINKS

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

Index entries for linear recurrences with constant coefficients, signature (1,0,0,110,-110,0,0,-1,1).

FORMULA

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)).

EXAMPLE

8 is in the sequence because 8^2 + ... + 28^2 = 7574 = 42^2 + ... + 45^2.

PROG

(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))

CROSSREFS

Cf. A157092, A246642, A261995.

Sequence in context: A188148 A316466 A100583 * A036464 A000938 A252871

Adjacent sequences:  A261993 A261994 A261995 * A261997 A261998 A261999

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Sep 08 2015

STATUS

approved

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Last modified August 24 23:01 EDT 2019. Contains 326314 sequences. (Running on oeis4.)