%I #47 Apr 04 2016 10:33:32
%S 6,9,12,15,18,20,21,24,27,30,33,36,39,40,42,45,48,50,51,54,57,60,63,
%T 66,69,70,72,75,78,80,81,84,87,90,93,96,99,100,102,105,108,110,111,
%U 114,117,120,123,126,129,130,132,135,138,140,141,144,147
%N Numbers of the form A001700(n)*k, n>=1, k>=2.
%C Numbers that are central coefficients T(2k,k) k>=2 in (a,b)-Pascal triangles, where (a,b) represent boundary conditions; i.e., T(2k,k) = (a+b)*A001700(k-1).
%F a(n) ~ kn, where k = 2.441823902640895564.... (This constant exists since A001700 grows exponentially.) - _Charles R Greathouse IV_, Apr 04 2016
%e a(n)=50 appears because A001700(2)=10, so T(6,3)=50 in (1,4)- and (2,3)-Pascal triangles.
%o (PARI) is(n)=my(k=1,t=3); while(n>=2*t, if(n%t==0, return(1)); k++; t=binomial(2*k+1, k+1)); 0 \\ _Charles R Greathouse IV_, Apr 04 2016
%Y Cf. A001700.
%Y Cf. A007318 (Pascal's triangle), A029600 ((2,3)-Pascal triangle), A095666 ((1,4)-Pascal triangle).
%K nonn,easy
%O 1,1
%A _Bob Selcoe_, Mar 31 2016