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A024392 a(n) = 3rd elementary symmetric function of the first n+2 positive integers congruent to 2 mod 3. 3
80, 806, 4040, 14155, 39655, 95200, 204036, 400830, 734910, 1273910, 2107820, 3353441, 5159245, 7710640, 11235640, 16010940, 22368396, 30701910, 41474720, 55227095, 72584435, 94265776, 121092700, 153998650, 194038650, 242399430 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..26.

Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).

FORMULA

a(n) = n*(n+1)*(n+2)*(3*n+7)*(9*n^2+33*n+22)/48.

G.f.  -x*(80+246*x+78*x^2+x^3) /  (x-1)^7 . - R. J. Mathar, Oct 08 2011

CROSSREFS

Sequence in context: A164753 A279745 A062911 * A200550 A052519 A246545

Adjacent sequences:  A024389 A024390 A024391 * A024393 A024394 A024395

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified May 21 19:00 EDT 2019. Contains 323444 sequences. (Running on oeis4.)