

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
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OFFSET

0,3


COMMENTS

The evennumbered terms are the same as the three  quarter squares; the oddnumbered 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(n2) + 3*(n1) for n>1, a(0) = a(1) = 0.
G.f.: 3*x^2/((1x)^2*(1x^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



