|
Search: id:A103975
|
|
|
| A103975 |
|
Smaller side in (a,a+1,a+1)-integer triangle with integer area. |
|
+0
5
|
|
| 16, 240, 3360, 46816, 652080, 9082320, 126500416, 1761923520, 24540428880, 341804080816, 4760716702560, 66308229755040, 923554499868016, 12863454768397200, 179164812257692800, 2495443916839302016
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
FORMULA
|
a(n) = 15*a(n-1) - 15*a(n-2) + a(n-3) - Max Alekseyev (maxale(AT)gmail.com), May 31 2007
a(n) = 2*A120892(2*n+1) - Max Alekseyev (maxale(AT)gmail.com), May 31 2007
a(n)=1/3*((2 - Sqrt(3))^(1 + 2*n) + (2 + Sqrt(3))^(1 + 2*n) - 4) [From Terentyev Oleg (terentyev_math(AT)i.ua), Nov 12 2009]
|
|
MATHEMATICA
|
a[n_] := 1/3 (-4 + (2 - Sqrt[3])^(1 + 2 n) + (2 + Sqrt[3])^(1 + 2 n)); A103975 = Expand[a /@ Range[1, 25]] [From Terentyev Oleg (terentyev_math(AT)i.ua), Nov 12 2009]
|
|
CROSSREFS
|
Cf. A102341, A103974, A016064, A011945, A103772.
Equals (4/3) (A001570(n) - 1).
Corresponding areas are given by A104008.
Sequence in context: A119463 A111096 A161591 this_sequence A060198 A097829 A010559
Adjacent sequences: A103972 A103973 A103974 this_sequence A103976 A103977 A103978
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Zak Seidov (zakseidov(AT)yahoo.com), Feb 23 2005
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 24 2005
|
|
|
Search completed in 0.002 seconds
|
