A022911 - OEIS

%I #18 May 23 2019 04:00:55

%S 4,5,6,6,7,8,7,9,10,11,8,12,8,13,9,14,15,16,10,9,17,18,11,19,20,21,10,

%T 12,22,10,23,24,13,25,26,11,27,14,28,29,30,15,11,31,12,32,33,16,34,35,

%U 36,37,17,38,13,39,40,12,18,41,42,43,12,44,19,45,14,46,47,48

%N Arrange the nontrivial binomial coefficients C(m,k) (2 <= k <= m/2) in increasing order (not removing duplicates); record the sequence of m's.

%C In case of duplicates, the m values are listed in decreasing order.  Thus a(18)=16 and a(19)=10 corresponding to binomial(16,2)=binomial(10,3)=120. - _Robert Israel_, Sep 18 2018

%H Robert Israel, <a href="/A022911/b022911.txt">Table of n, a(n) for n = 1..10000</a>

%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a022/A022911.java">Java program</a> (github)

%F A319382(n) = binomial(a(n),A022912(n)). - _Robert Israel_, Sep 18 2018

%p N:= 10000: # for binomial(n,k) values <= N

%p Res:= NULL:

%p for n from 2 while n*(n-1)/2 <= N do

%p   for k from 2 to n/2 do

%p     v:= binomial(n,k);

%p     if v > N then break fi;

%p     Res:= Res,[v,n,k]

%p od od:

%p Res:= sort([Res],proc(p,q) if p[1]<>q[1] then  p[1]<q[1]

%p   elif p[2]<>q[2] then p[2]>q[2]

%p   fi end proc):

%p map(t -> t[2], Res); # _Robert Israel_, Sep 18 2018

%Y Cf. A003015, A006987, A022912, A319382.

%K nonn

%O 1,1

%A _Clark Kimberling_