A244636 a(n) = 30*n^2.

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, 50430

Offset: 0

Author

Vincenzo Librandi, Jul 03 2014

Keywords

• nonn
• easy

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

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Crossrefs

Cf. similar sequences listed in A244630.

Cf. A000290, A001105, A033428, A033429, A033581, A033583, A064761, A249674, A330451.

Programs

Magma

[30*n^2: n in [0..40]];

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 *)

PARI

a(n)=30*n^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 30*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]

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

From Elmo R. Oliveira, Dec 02 2024: (Start)

E.g.f.: 30*x*(1 + x)*exp(x).

a(n) = n*A249674(n) = A330451(3*n). (End)