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A145322
Numbers n such that there exists x in N : (x+1)^3-x^3=31*n^2.
1
7, 170107, 4133940307, 100463017170607, 2441452239146151007, 59332172215266744601507, 1441890446733960188159672107, 35040821577196528277389606942807, 851562044527139583463162039764423607, 20694660771057724580125235612965415554507
OFFSET
1,1
FORMULA
a(n+2) = 24302*a(n+1)-a(n).
G.f.: -7*x*(x-1) / (x^2-24302*x+1). - Colin Barker, Oct 19 2014
EXAMPLE
a(1)=7 because 23^3-22^3=31*7^2.
MATHEMATICA
LinearRecurrence[{24302, -1}, {7, 170107}, 10] (* Paolo Xausa, Jan 17 2024 *)
PROG
(PARI) Vec(-7*x*(x-1)/(x^2-24302*x+1) + O(x^20)) \\ Colin Barker, Oct 19 2014
CROSSREFS
Sequence in context: A243859 A297059 A306256 * A145335 A003835 A138878
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, Oct 07 2008
EXTENSIONS
Editing and a(10) from Colin Barker, Oct 19 2014
STATUS
approved