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A144930
Numbers k arising in A144929.
6
1, 109, 11989, 1318681, 145042921, 15953402629, 1754729246269, 193004263686961, 21228714276319441, 2334965566131451549, 256824983560183350949, 28248413226054037152841, 3107068629882383903461561, 341749300873836175343618869, 37589316027492096903894614029
OFFSET
1,2
COMMENTS
Numbers n such that there exists x in N : (x+1)^3 - x^3 = 7*n^2. - Richard Choulet, Oct 16 2008
REFERENCES
E.-A. Majol, Note #2228, L'Intermédiaire des Mathématiciens, 9 (1902), pp. 183-185. - N. J. A. Sloane, Mar 03 2022
FORMULA
a(n+2) = 110*a(n+1)-a(n). - Richard Choulet, Oct 16 2008
G.f.: -x*(x-1) / (x^2-110*x+1). - Colin Barker, Oct 17 2014
EXAMPLE
a(1) = 1 because 2^3-1^3 = 7*1. - Richard Choulet, Oct 16 2008
MATHEMATICA
LinearRecurrence[{110, -1}, {1, 109}, 20] (* Harvey P. Dale, Oct 05 2016 *)
PROG
(PARI) Vec(-x*(x-1)/(x^2-110*x+1) + O(x^20)) \\ Colin Barker, Jul 14 2016
CROSSREFS
Sequence in context: A280626 A357231 A227949 * A190827 A125044 A352466
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, Sep 25 2008
EXTENSIONS
More terms from Colin Barker, Oct 17 2014
STATUS
approved