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A144044
a(n) = ((1+sqrt(11))^n-(1-sqrt(11))^n)^2/44.
0
1, 4, 196, 2304, 55696, 906304, 18181696, 325730304, 6199357696, 114211554304, 2141141533696, 39766241378304, 742275639709696, 13817991215202304, 257604225193885696, 4798702283133026304, 89428432275804061696
OFFSET
1,2
COMMENTS
Sequences of the form a(n) = ((A+sqrt B)^n-(A-sqrt B)^n)^2/(4B) have recurrences a(n) = (3A^2+B) *a(n-1) +(B+3A^2)*(B-A^2) *a(n-2) -(B-A^2)^3*a(n-3) and generating functions x(1+(A^2-B)x) / ((1 -(A^2-B)x)(1-2(A^2+B)x +(A^4-2A^2B+B^2)x^2)). - R. J. Mathar, Nov 01 2008
FORMULA
From R. J. Mathar, Nov 01 2008: (Start)
a(n) = 14*a(n-1)+140*a(n-2)-1000*a(n-3).
G.f. x(1-10x)/((10x+1)(1-24x+100x^2)). (End)
CROSSREFS
Sequence in context: A042127 A219163 A017546 * A221197 A180991 A279803
KEYWORD
nonn,easy
AUTHOR
Al Hakanson (hawkuu(AT)gmail.com), Sep 08 2008
EXTENSIONS
More terms from R. J. Mathar, Nov 01 2008
STATUS
approved