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

1,3

Links

Table of n, a(n) for n=1..21.

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.

Maple

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

Prog

(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

Crossrefs

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

Sequence in context: A308231 A179594 A374947 * A263417 A053848 A347608

Adjacent sequences: A196746 A196747 A196748 * A196750 A196751 A196752

Keyword

nonn,more

Author

Peter Luschny, Oct 06 2011

Status

approved