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A047866 a(n) = ceiling(n*(n+1)*(n+2)/8). 5
0, 1, 3, 8, 15, 27, 42, 63, 90, 124, 165, 215, 273, 342, 420, 510, 612, 727, 855, 998, 1155, 1329, 1518, 1725, 1950, 2194, 2457, 2741, 3045, 3372, 3720, 4092, 4488, 4909, 5355, 5828, 6327, 6855, 7410, 7995, 8610, 9256, 9933, 10643, 11385 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A lower bound to Honaker's triangle problem A047837.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,0,0,0,1,-3,3,-1).

FORMULA

G.f.: x*(1 + 2*x^2 - x^3 + 3*x^4 - 2*x^5 + 3*x^6)/((1-x)^4*(1+x)*(1+x^2)*(1+x^4)). - R. J. Matharq, Mar 11 2012

PROG

(MAGMA) [Ceiling( n*(n+1)*(n+2)/8 ) : n in [0..50]]; // Vincenzo Librandi, Sep 28 2011

(PARI) a(n)=(n*(n+1)*(n+2)+6)\8 \\ Charles R Greathouse IV, Oct 07 2015

CROSSREFS

Cf. A047837.

Sequence in context: A048598 A049717 A241565 * A080183 A109900 A034828

Adjacent sequences:  A047863 A047864 A047865 * A047867 A047868 A047869

KEYWORD

nonn,easy

AUTHOR

Mike Keith (domnei(AT)aol.com)

STATUS

approved

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Last modified January 17 17:22 EST 2022. Contains 350402 sequences. (Running on oeis4.)