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A156718 Numbers n such that n^2 == -1 mod 13^2. 4
70, 99, 239, 268, 408, 437, 577, 606, 746, 775, 915, 944, 1084, 1113, 1253, 1282, 1422, 1451, 1591, 1620, 1760, 1789, 1929, 1958, 2098, 2127, 2267, 2296, 2436, 2465, 2605, 2634, 2774, 2803, 2943, 2972, 3112, 3141, 3281, 3310, 3450, 3479, 3619, 3648, 3788 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Also, numbers of the form 169n +- 70.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).

FORMULA

a(n) = a(n-1) +a(n-2) -a(n-3).

G.f.: x*(70+29*x+70*x^2) / ( (1+x)*(x-1)^2 ). [From Alexander R. Povolotsky (pevnev(AT)juno.com), Feb 15 2009]

MATHEMATICA

LinearRecurrence[{1, 1, -1}, {70, 99, 239}, 50]

PROG

(MAGMA) [Floor(n/2)*169-70*(-1)^n: n in [1..50]];

(PARI) a(n)=n\2*169-70*(-1)^n \\ Charles R Greathouse IV, Dec 23 2011

CROSSREFS

Cf. A156636, A156640, A156627, A156639.

Sequence in context: A036191 A165632 A136117 * A007621 A051971 A180274

Adjacent sequences:  A156715 A156716 A156717 * A156719 A156720 A156721

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Feb 14 2009

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Last modified February 14 15:39 EST 2012. Contains 205635 sequences.