|
| |
|
|
A153169
|
|
4n^2 + 12n + 3.
|
|
0
| |
|
|
19, 43, 75, 115, 163, 219, 283, 355, 435, 523, 619, 723, 835, 955, 1083, 1219, 1363, 1515, 1675, 1843, 2019, 2203, 2395, 2595, 2803, 3019, 3243, 3475, 3715, 3963, 4219, 4483, 4755, 5035
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Sequence gives values of x such that x^3+6x^2=y^2 since a(n)^3+6*a(n)^2=(8n^3+36n^2+42n+9)^2.
The complete list of nonnegative values of x in x^3 + 6x^2 = y^2 is given by A028878. - Bruno Berselli, Jan 25 2012
|
|
|
FORMULA
| a(1)=19, a(2)=43, a(3)=75, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). G.f.: x*(19-14*x+3*x^2)/(1-x)^3. - Colin Barker, Jan 24 2012
|
|
|
EXAMPLE
| for n=1 then a(1)=19=X; 19^3+6*19^2=95^2
|
|
|
CROSSREFS
| Cf. A153167.
Sequence in context: A094845 A155770 A036061 * A090797 A078561 A074222
Adjacent sequences: A153166 A153167 A153168 * A153170 A153171 A153172
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Dec 20 2008
|
|
|
EXTENSIONS
| Definition rewritten by Bruno Berselli, Jan 25 2012
|
| |
|
|
