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A244636
a(n) = 30*n^2.
7
0, 30, 120, 270, 480, 750, 1080, 1470, 1920, 2430, 3000, 3630, 4320, 5070, 5880, 6750, 7680, 8670, 9720, 10830, 12000, 13230, 14520, 15870, 17280, 18750, 20280, 21870, 23520, 25230, 27000, 28830, 30720, 32670, 34680, 36750, 38880, 41070, 43320, 45630, 48000
OFFSET
0,2
COMMENTS
Sequence found by reading the line from 0, in the direction 0, 30,..., in the square spiral whose vertices are the generalized 17-gonal numbers. - Omar E. Pol, Jul 03 2014
FORMULA
G.f.: 30*x*(1 + x)/(1 - x)^3.
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3) for n>2.
a(n) = 30*A000290(n) = 15*A001105(n) = 10*A033428(n) = 6*A033429(n) = 5*A033581(n) = 3*A033583(n) = 2*A064761(n). - Omar E. Pol, Jul 03 2014
MAPLE
A244636:=n->30*n^2: seq(A244636(n), n=0..50); # Wesley Ivan Hurt, Jul 04 2014
MATHEMATICA
Table[30 n^2, {n, 0, 40}]
CoefficientList[Series[30x (1+x)/(1-x)^3, {x, 0, 50}], x] (* or *) LinearRecurrence[ {3, -3, 1}, {0, 30, 120}, 50] (* Harvey P. Dale, Dec 02 2021 *)
PROG
(Magma) [30*n^2: n in [0..40]];
(PARI) a(n)=30*n^2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Cf. similar sequences listed in A244630.
Sequence in context: A232775 A246766 A112955 * A290391 A277451 A042764
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jul 03 2014
EXTENSIONS
G.f. corrected by Bruno Berselli, Jul 03 2014
STATUS
approved