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A115273 Floor(n/3)*(n mod 3). 9
0, 0, 0, 0, 1, 2, 0, 2, 4, 0, 3, 6, 0, 4, 8, 0, 5, 10, 0, 6, 12, 0, 7, 14, 0, 8, 16, 0, 9, 18, 0, 10, 20, 0, 11, 22, 0, 12, 24, 0, 13, 26, 0, 14, 28, 0, 15, 30, 0, 16, 32, 0, 17, 34, 0, 18, 36, 0, 19, 38, 0, 20, 40, 0, 21, 42, 0, 22, 44, 0, 23, 46, 0, 24, 48, 0, 25, 50, 0, 26, 52, 0, 27, 54, 0, 28, 56 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

Three arithmetic progressions interlaced: a(1)=1,2,0 and d=a(n+1)-a(n)=1,2,0. Cf. A115274(n) = n+a(n), n=1,2,3,...

LINKS

Table of n, a(n) for n=0..86.

FORMULA

a(3k+1) = k, a(3k+2) = 2k, a(3k+3) = 0, k=1, 2, ...

G.f.: x^4*(2*x+1) / ((x-1)^2*(x^2+x+1)^2). - Colin Barker, May 11 2015

MATHEMATICA

Table[Floor[n/3]*Mod[n, 3], {n, 0, 104}] \\ Extended to offset 0 by M. F. Hasler, May 11 2015

PROG

(PARI) a(n, b=3)=(n=divrem(n, b))[1]*n[2] \\ M. F. Hasler, May 10 2015

(MAGMA) [Floor(n/3)*(n mod 3): n in [0..100]]; // Vincenzo Librandi, May 11 2015

CROSSREFS

Cf. A115274.

Cf. A142150 (the base 2 analog), A257844, ..., A257850.

Sequence in context: A199335 A141660 A209699 * A194759 A209697 A126440

Adjacent sequences:  A115270 A115271 A115272 * A115274 A115275 A115276

KEYWORD

nonn,easy

AUTHOR

Zak Seidov, Jan 18 2006

EXTENSIONS

Added a(0)-a(3) and cross-references. M. F. Hasler, May 11 2015

STATUS

approved

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Last modified February 21 01:15 EST 2019. Contains 320364 sequences. (Running on oeis4.)