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 A196749 #9 Feb 03 2016 11:39:57 %S A196749 0,1,2,20,1512,1513,1514,6320,6372,6373,6374,6500,15120,15121,15122, %T A196749 15302,40014,119096754,119096802,91547225622,91550794374 %N A196749 Numbers n such that 3, 5 and 7 do not divide swing(n) = A056040(n). %H A196749 P. Erdos, R. L. Graham, I. Z. Russa and E. G. Straus, <a href="http://www.math.ucsd.edu/~ronspubs/75_03_prime_factors.pdf">On the prime factors of C(2n,n)</a>, Math. Comp. 29 (1975), 83-92. %H A196749 Peter Luschny, <a href="http://oeis.org/wiki/User:Peter_Luschny/PrimeFactorsSwingingFactorial">On the prime factors of the swinging factorial</a>. %p A196749 # The function Search is defined in A196747. %p A196749 A196749_list := n -> Search(n,[3,5,7]): # n is a search limit %o A196749 (PARI) valp(n,p)=my(s); while(n\=p, s+=n); s %o A196749 is(n)=valp(n,3)==2*valp(n\2,3) && valp(n,5)==2*valp(n\2,5) && valp(n,7)==2*valp(n\2,7) \\ _Charles R Greathouse IV_, Feb 02 2016 %Y A196749 Cf. A005836, A129508, A030979, A151750, A196747, A196748, A196750. %K A196749 nonn,more %O A196749 1,3 %A A196749 _Peter Luschny_, Oct 06 2011