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 A268432 #14 Jan 29 2019 02:17:06 %S A268432 1,1,2,60,56,15120,15840,8648640,17297280,8821612800,10158220800, %T A268432 14079294028800,474467051520,32382376266240000,582882772792320000, %U A268432 101421602465863680000,24659370011308032000,415017197290314178560000,72810034612335820800000,2149789081963827444940800000 %N A268432 a(n) = Pochhammer(n+1, n)/Clausen(n, 1) = A001813(n) / A160014(n, 1). %F A268432 Let b(n) = Pochhammer(n+1,n)/denominator(Bernoulli(n)) then a(2*n) = b(2*n) for n >= 0 and 2*a(2*n+1) = b(2*n+1) for n >= 1 by the von Staudt-Clausen theorem. %p A268432 a := proc(n) numtheory[divisors](n); map(i->i+1, %); %p A268432 iquo(mul(4*k+2,k in (0..n-1)), mul(k,k in select(isprime, %))) end: %p A268432 seq(a(n), n=0..19); %o A268432 (Sage) %o A268432 def A268432(n): %o A268432 if n <= 1: return 1 %o A268432 r = rising_factorial(n+1,n)//bernoulli(n).denominator() %o A268432 return r if is_even(n) else r//2 %o A268432 [A268432(n) for n in range(20)] %Y A268432 Cf. A001813, A027642, A160014, A264437. %K A268432 nonn %O A268432 0,3 %A A268432 _Peter Luschny_, Feb 14 2016