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A242477 Floor(3*n^2/4). 3
0, 0, 3, 6, 12, 18, 27, 36, 48, 60, 75, 90, 108, 126, 147, 168, 192, 216, 243, 270, 300, 330, 363, 396, 432, 468, 507, 546, 588, 630, 675, 720, 768, 816, 867, 918, 972, 1026, 1083, 1140, 1200, 1260, 1323, 1386, 1452, 1518, 1587, 1656, 1728, 1800, 1875 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The even-numbered terms are the same as the three - quarter squares; the odd-numbered terms are one less.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Craig Knecht, Maximum number of octiamonds in a hexagon.

Robert Munafo, Sequence MCS429697

Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1).

FORMULA

a(n) = a(n-2) + 3*(n-1) for n>1, a(0) = a(1) = 0.

G.f.: 3*x^2/((1-x)^2*(1-x^2)). [Bruno Berselli, May 22 2014]

a(n) = 3*A002620(n). [Bruno Berselli, May 22 2014]

MATHEMATICA

Table[Floor[3 n^2/4], {n, 0, 60}]

LinearRecurrence[{2, 0, -2, 1}, {0, 0, 3, 6}, 60] (* Harvey P. Dale, Sep 07 2019 *)

PROG

(MAGMA) [Floor(3*n^2/4): n in [0..60]];

(Sage) [3*floor(n^2/4) for n in (0..60)] # Bruno Berselli, May 22 2014

CROSSREFS

Cf. A002620.

Sequence in context: A181026 A180005 A116958 * A006156 A171370 A061776

Adjacent sequences:  A242474 A242475 A242476 * A242478 A242479 A242480

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, May 22 2014

STATUS

approved

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Last modified July 29 17:41 EDT 2021. Contains 346346 sequences. (Running on oeis4.)