A196749 Numbers n such that 3, 5 and 7 do not divide swing(n) = A056040(n).

0, 1, 2, 20, 1512, 1513, 1514, 6320, 6372, 6373, 6374, 6500, 15120, 15121, 15122, 15302, 40014, 119096754, 119096802, 91547225622, 91550794374

Offset: 1

Author

Peter Luschny, Oct 06 2011

Keywords

• nonn
• more

Links

• P. Erdos, R. L. Graham, I. Z. Russa and E. G. Straus, On the prime factors of C(2n,n), Math. Comp. 29 (1975), 83-92.
• Peter Luschny, On the prime factors of the swinging factorial.

Crossrefs

Cf. A005836, A129508, A030979, A151750, A196747, A196748, A196750.

Programs

Maple

# The function Search is defined in A196747.
A196749_list := n -> Search(n,[3,5,7]):  # n is a search limit

PARI

valp(n,p)=my(s); while(n\=p, s+=n); s
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