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A145320 Numbers n such that there exists x in N : (x+31)^3-x^3=n^2. 0
6727, 163472827, 3972716635027, 96544959500953327, 2346235601819451117727, 57018217498871341562048227, 1385656719311335740821444894827, 33674229535685863674571412272037527, 818351124790581139708098720213611086327 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..9.

Index entries for linear recurrences with constant coefficients, signature (24302,-1).

FORMULA

a(n+2) = 24302*a(n+1)-a(n).

a(n) = (1395/4)*sqrt(93)*{[12151+1260*sqrt(93)]^n-[12151-1260*sqrt(93)]^n}+(6727/2)*{[12151+1260*sqrt(93)]^n+[12151-1260*sqrt(93)]^n}, with n>=0. - Paolo P. Lava, Nov 25 2008

G.f.: -6727*x*(x-1) / (x^2-24302*x+1). - Colin Barker, Oct 17 2014

EXAMPLE

a(1)=6727 because the first relation is : (682+31)^3-682^3=6727^2.

PROG

(PARI) Vec(-6727*x*(x-1)/(x^2-24302*x+1) + O(x^20)) \\ Colin Barker, Oct 17 2014

CROSSREFS

Sequence in context: A237041 A031580 A028543 * A099778 A035905 A049507

Adjacent sequences:  A145317 A145318 A145319 * A145321 A145322 A145323

KEYWORD

nonn,easy

AUTHOR

Richard Choulet, Oct 07 2008

EXTENSIONS

a(9) from Colin Barker, Oct 17 2014

STATUS

approved

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Last modified July 18 15:44 EDT 2019. Contains 325144 sequences. (Running on oeis4.)