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 A080497 #9 Dec 01 2018 07:59:17
%S A080497 1,1,1,2,6,12,40,90,336,840,1728,3150,10560,24948,99840,270270,604800,
%T A080497 1201200,4386816,11277630,49029120,143896500,348364800,746876130,
%U A080497 2937876480,8117240040,18923520000,39628338750,76859228160,140548508100
%N A080497 a(n) = (n-p_1)(n-p_2)...(n-p_k) where p_k is the k-th prime and is also the largest prime < n.
%e A080497 a(6) = (6-2)(6-3)(6-5) = 12. a(7) = (7-2)(7-3)(7-5) = 40.
%t A080497 a[n_] := Product[n - Prime[k], {k, 1, PrimePi[n - 1]}]; Array[a, 30] (* _Amiram Eldar_, Dec 01 2018 *)
%o A080497 (PARI) a(n) = my(mk = primepi(n-1)); prod(k=1, mk, n-prime(k)); \\ _Michel Marcus_, Dec 01 2018
%Y A080497 Cf. A080498, A072513, A080500.
%K A080497 nonn
%O A080497 1,4
%A A080497 _Amarnath Murthy_, Mar 19 2003
%E A080497 More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003