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A050494 Partial sums of A051923. 3
1, 10, 52, 192, 570, 1452, 3300, 6864, 13299, 24310, 42328, 70720, 114036, 178296, 271320, 403104, 586245, 836418, 1172908, 1619200, 2203630, 2960100, 3928860, 5157360, 6701175, 8625006, 11003760, 13923712, 17483752, 21796720, 26990832, 33211200, 40621449 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

If Y is a 3-subset of an n-set X then, for n>=9, a(n-9) is the number of 9-subsets of X having at least two elements in common with Y. - Milan Janjic, Nov 23 2007

REFERENCES

A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.

LINKS

Table of n, a(n) for n=0..32.

Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1)

FORMULA

a(n)=C(n+6, 6)*(3n+7)/7.

G.f.: (1+2*x)/(1-x)^8.

MATHEMATICA

Table[Binomial[n+6, 6]*(3*n+7)/7, {n, 0, 50}] (* Vladimir Joseph Stephan Orlovsky, Jan 27 2012 *)

CROSSREFS

Cf. A051923.

Cf. A093560 ((3, 1) Pascal, column m=7).

Sequence in context: A257042 A092966 A281401 * A200035 A119543 A216938

Adjacent sequences:  A050491 A050492 A050493 * A050495 A050496 A050497

KEYWORD

easy,nonn

AUTHOR

Barry E. Williams, Dec 26 1999

STATUS

approved

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Last modified February 24 22:22 EST 2018. Contains 299627 sequences. (Running on oeis4.)