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A006987 Binomial coefficients: C(n,k), 2 <= k <= n-2, sorted, duplicates removed.

%I A006987 M4084 #70 Dec 13 2018 02:47:21
%S A006987 6,10,15,20,21,28,35,36,45,55,56,66,70,78,84,91,105,120,126,136,153,
%T A006987 165,171,190,210,220,231,252,253,276,286,300,325,330,351,364,378,406,
%U A006987 435,455,462,465,495,496,528,560,561,595,630,666,680,703,715,741,780,792,816,820
%N A006987 Binomial coefficients: C(n,k), 2 <= k <= n-2, sorted, duplicates removed.
%C A006987 Complement of A137905; a(n) > A058084(a(n)). - _Reinhard Zumkeller_, Mar 20 2009
%C A006987 Or numbers l which, for the first time, appear in m-th row of the Pascal triangle for m < l. - _Vladimir Shevelev_, Apr 28 2010
%C A006987 Appears to be the set of simplex numbers of order > 2 and dimension > 1. - _Dylan Hamilton_, Nov 05 2010
%C A006987 This is correct (assuming the notational choice of giving the first n-simplicial number index 1), as the n-th diagonal or antidiagonal of Pascal's triangle gives the n-simplicial numbers. - _Thomas Anton_, Dec 04 2018
%D A006987 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006987 David A. Corneth, <a href="/A006987/b006987.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from T. D. Noe)
%H A006987 R. G. Wilson v, <a href="/A126333/a126333.pdf">Letter to N. J. A. Sloane, Nov. 1988</a>
%H A006987 R. G. Wilson v, <a href="/A006987/a006987.pdf">Letter to N. J. A. Sloane, Jan. 1989</a>
%e A006987 Pascal's triangle (A007318) with the outer two layers removed:
%e A006987              6
%e A006987           10  10
%e A006987         15  20  15
%e A006987       21  35  35  21
%e A006987     28  56  70  56  28
%e A006987   36  84 126 126  84  36
%e A006987   ...
%t A006987 Take[ Union[ Flatten[ Table[ Binomial[n, k], {n, 2, 45}, {k, 2, n - 2}]]], 58] (* _Robert G. Wilson v_, May 25 2004 *)
%o A006987 (PARI) list(lim)=my(v=List(), t); for(n=4, sqrtint(2*lim)+1, for(k=2, n\2, t=binomial(n, k); if(t>lim, break, listput(v, t)))); vecsort(Vec(v), , 8) \\ _Charles R Greathouse IV_, Apr 03 2012
%Y A006987 Cf. A002808, A007318.
%K A006987 nonn
%O A006987 1,1
%A A006987 _N. J. A. Sloane_, _Robert G. Wilson v_
%E A006987 More terms from _David W. Wilson_
%E A006987 Spelling corrected by _Jason G. Wurtzel_, Aug 22 2010