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A157796
a(n) = 27225*n^2 - 12098*n + 1344.
3
16471, 86048, 210075, 388552, 621479, 908856, 1250683, 1646960, 2097687, 2602864, 3162491, 3776568, 4445095, 5168072, 5945499, 6777376, 7663703, 8604480, 9599707, 10649384, 11753511, 12912088, 14125115, 15392592, 16714519
OFFSET
1,1
COMMENTS
The identity(1482401250*n^2-658736100*n+73180801)^2-(27225*n^2-12098*n+1344)*(8984250*n-1996170)^2=1 can be written as A157798(n)^2-a(n)*A157797(n)^2=1.
FORMULA
G.f.: x*(16471 + 36635*x + 1344*x^2)/(1 - x)^3.
a(1)=16471, a(2)=86048, a(3)=210075; for n>3, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Jul 02 2011
MATHEMATICA
Table[27225 n^2 - 12098 n + 1344, {n, 25}] (* Harvey P. Dale, Feb 20 2011 *)
LinearRecurrence[{3, -3, 1}, {16471, 86048, 210075}, 25] (* Harvey P. Dale, Jul 02 2011 *)
PROG
(Magma) I:=[16471, 86048, 210075]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+Self(n-3): n in [1..40]];
(PARI) a(n)=27225*n^2-12098*n+1344;
CROSSREFS
Sequence in context: A283027 A031829 A057680 * A186848 A211841 A234054
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 07 2009
EXTENSIONS
Edited by M. F. Hasler, Oct 08 2014
STATUS
approved