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 A196748 #15 Feb 03 2016 11:38:32 %S A196748 0,1,2,20,24,54,60,61,62,72,73,74,504,510,511,512,560,564,1512,1513, %T A196748 1514,1520,1620,1621,1622,6320,6324,6372,6373,6374,6500,6504,6552, %U A196748 6553,6554,6560,13122,13123,13124,13770,13771,13772,13824,13850,15072,15073,15074 %N A196748 Numbers n such that 3 and 5 do not divide swing(n) = A056040(n). %H A196748 Charles R Greathouse IV, <a href="/A196748/b196748.txt">Table of n, a(n) for n = 1..1000</a> %H A196748 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 A196748 Peter Luschny, <a href="http://oeis.org/wiki/User:Peter_Luschny/PrimeFactorsSwingingFactorial">On the prime factors of the swinging factorial</a>. %p A196748 # The function Search is defined in A196747. %p A196748 A196748_list := n -> Search(n,[3,5]): # n is a search limit %t A196748 (* A naive solution *) sf[n_] := n!/Quotient[n, 2]!^2; Select[Range[0, 16000], !Divisible[sf[#], 3] && !Divisible[sf[#], 5] &] (* _Jean-François Alcover_, Jun 28 2013 *) %o A196748 (PARI) valp(n,p)=my(s); while(n\=p, s+=n); s %o A196748 is(n)=valp(n,3)==2*valp(n\2,3) && valp(n,5)==2*valp(n\2,5) \\ _Charles R Greathouse IV_, Feb 02 2016 %Y A196748 Cf. A005836, A129508, A030979, A151750, A196747, A196749, A196750. %K A196748 nonn %O A196748 1,3 %A A196748 _Peter Luschny_, Oct 06 2011