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A173511 a(n) = 4*n^2 + floor(n/2). 7
0, 4, 17, 37, 66, 102, 147, 199, 260, 328, 405, 489, 582, 682, 791, 907, 1032, 1164, 1305, 1453, 1610, 1774, 1947, 2127, 2316, 2512, 2717, 2929, 3150, 3378, 3615, 3859, 4112, 4372, 4641, 4917, 5202, 5494, 5795, 6103, 6420, 6744, 7077, 7417, 7766, 8122 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n+1) - a(n) = A173512(n).

a(n) = A002943(n) - A007494(n) = A007742(n) - A110654(n).

a(2*n) = A157474(n) for n>0.

LINKS

Table of n, a(n) for n=0..45.

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

FORMULA

a(n) = floor((2*n + 1/8)^2).

a(n)= 2*a(n-1) -2*a(n-3) +a(n-4). G.f.: -x*(4+9*x+3*x^2)/((1+x)*(x-1)^3). - R. J. Mathar, Feb 21 2010

EXAMPLE

a(6) = 147; 4(6)^2 + floor(6/3) = 144 + 3 = 147.

MAPLE

A173511:=n->4*n^2 + floor(n/2); seq(A173511(k), k=0..100); # Wesley Ivan Hurt, Nov 01 2013

MATHEMATICA

Table[4n^2 + Floor[n/2], {n, 0, 100}] (* Wesley Ivan Hurt, Nov 01 2013 *)

PROG

(PARI) a(n) = 4*n^2 + n\2 \\ Charles R Greathouse IV, Jun 11 2015

CROSSREFS

Sequence in context: A120884 A267766 A273683 * A218925 A182868 A178947

Adjacent sequences:  A173508 A173509 A173510 * A173512 A173513 A173514

KEYWORD

nonn,easy

AUTHOR

Reinhard Zumkeller, Feb 20 2010

STATUS

approved

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Last modified June 20 19:36 EDT 2019. Contains 324234 sequences. (Running on oeis4.)