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A056556 First tetrahedral co-ordinate; repeat m (m+1)*(m+2)/2 times. 14
0, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

If {(X,Y,Z)} are triples of nonnegative integers with X>=Y>=Z ordered by X, Y and Z, then X=A056556(n), Y=A056557(n) and Z=A056558(n)

LINKS

Table of n, a(n) for n=0..104.

FORMULA

a(n)=floor[x] where x is the (largest real) solution to x^3+3x^2+2x-6n=0; a(A000292(n))=n+1

a(n+1) = a(n)==A056558(n) ? a(n)+1 : a(n) - Graeme McRae, Jan 09 2007

PROG

(PARI) a(n)=my(t=polrootsreal(x^3+3*x^2+2*x-6*n)); t[#t]\1 \\ Charles R Greathouse IV, Feb 22 2017

CROSSREFS

Cf. A000292, A003056, A056557, A056558, A056559, A056560.

See also A194847.

Sequence in context: A220104 A191228 A286103 * A111651 A151982 A259361

Adjacent sequences:  A056553 A056554 A056555 * A056557 A056558 A056559

KEYWORD

nonn,easy

AUTHOR

Henry Bottomley, Jun 26 2000

STATUS

approved

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Last modified January 17 10:59 EST 2019. Contains 319218 sequences. (Running on oeis4.)