This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A178607 #13 Feb 01 2018 03:31:06
%S A178607 2,7,13,47,103,383,941,3833,10391,46073,135131,645097,2027023,
%T A178607 10321919,34459423,185794463,654729073,3715891181,13749310511,
%U A178607 81749606383,316234143163,1961990553581,7905853580621,51011754393599
%N A178607 Largest prime < n!! (double factorial of n).
%H A178607 Vincenzo Librandi, <a href="/A178607/b178607.txt">Table of n, a(n) for n = 3..200</a>
%F A178607 a(n) = A151799(A006882(n)). - _R. J. Mathar_, Jun 23 2010
%t A178607 PrimePrev[n_]:=Module[{k},k=n-1;While[ !PrimeQ[k],k-- ];k]; Table[PrimePrev[n!! ],{n,3,40}]
%t A178607 NextPrime[#,-1]&/@(Range[3,30]!!) (* _Harvey P. Dale_, Jul 13 2015 *)
%o A178607 (PARI) a(n)=if(n<2, 1, n*a(n-2)); for(n=3,26,print1(precprime(a(n)-1)", ")); \\ Graziano Aglietti (mg5055(AT)mclink.it), Aug 23 2010
%Y A178607 Cf. A006882, A006990, A037151, A178606.
%K A178607 nonn
%O A178607 3,1
%A A178607 _Vladimir Joseph Stephan Orlovsky_, May 30 2010
%E A178607 Offset corrected by _R. J. Mathar_, Jun 23 2010