Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #6 Jul 31 2015 01:25:44
%S 6,20,56,36,11,13,680,3876,245157,34597290,84672315,12875774670,
%T 244662670200,800472431850,14833897694226,973469712824056,
%U 48402641245296107,191724747789809255,9989690752182277136
%N Let c = composite(n) & p = prime(n); a(n) = binomial( max(c,p), min(c,p) ).
%C 11 and 13 are the only prime terms. For a(7) onwards sequence is monotonically increasing.
%e a(3) = C(8,5) = 56, a(8) = C(19,15) =3876.
%t Composite[ n_Integer ] := Block[{k = n + PrimePi[ n ] + 1}, While[ k != n + PrimePi[ k ] + 1, k++ ]; k]; f[n_] := Block[{a = Sort[{Composite[n], Prime[n]}]}, Binomial[Last[a], First[a]]]; Table[ f[n], {n, 19}] (* _Robert G. Wilson v_, Jul 16 2005 *)
%K easy,nonn
%O 1,1
%A _Amarnath Murthy_, Jul 14 2005
%E More terms from _Robert G. Wilson v_, Jul 16 2005