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A195322 20*n^2. 6
0, 20, 80, 180, 320, 500, 720, 980, 1280, 1620, 2000, 2420, 2880, 3380, 3920, 4500, 5120, 5780, 6480, 7220, 8000, 8820, 9680, 10580, 11520, 12500, 13520, 14580, 15680, 16820, 18000, 19220, 20480, 21780, 23120, 24500, 25920, 27380, 28880, 30420, 32000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Sequence found by reading the line from 0, in the direction 0, 20,..., in the square spiral whose vertices are the generalized dodecagonal numbers A195162. Semi-axis opposite to A195317 in the same spiral.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

FORMULA

a(n) = 20*A000290(n) = 10*A001105(n) = 5*A016742(n) = 4*A033429(n) = 2*A033583(n).

a(0)=0, a(1)=20, a(2)=80, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Jan 18 2013

MATHEMATICA

20Range[0, 40]^2 (* or *) LinearRecurrence[{3, -3, 1}, {0, 20, 80}, 50] (* Harvey P. Dale, Jan 18 2013 *)

PROG

(MAGMA) [20*n^2:n in [0..40]]; // Vincenzo Librandi, Sep 20 2011

CROSSREFS

Bisection of A195148.

Cf. A033581, A139098, A033583, A135453, A144555, A016802, A195321, A195323.

Sequence in context: A083127 A211613 A002609 * A200424 A211463 A244449

Adjacent sequences:  A195319 A195320 A195321 * A195323 A195324 A195325

KEYWORD

nonn,easy

AUTHOR

Omar E. Pol, Sep 16 2011

STATUS

approved

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Last modified December 20 07:03 EST 2014. Contains 252241 sequences.