A246663 Products of swinging factorials A056040.

1, 2, 4, 6, 8, 12, 16, 20, 24, 30, 32, 36, 40, 48, 60, 64, 70, 72, 80, 96, 120, 128, 140, 144, 160, 180, 192, 216, 240, 252, 256, 280, 288, 320, 360, 384, 400, 420, 432, 480, 504, 512, 560, 576, 600, 630, 640, 720, 768, 800, 840, 864, 900, 960, 1008, 1024

Offset

1,2

Links

Table of n, a(n) for n=1..56.

Mathematica

sw[n_] := n!/(Floor[n/2]!)^2; lim = 40; For[p = 0; a = f = Table[sw[n], {n, lim}], p =!= a, p = a; a = Select[Union@@Outer[Times, f, a], #<= sw[lim]&]]; a (* Hans Havermann, Sep 09 2014 *)

Prog

(Sage)
# For example prod_hull(A008578) are the natural numbers.
def prod_hull(f, K):
    S = []; newS = []
    n = 0
    while f(n) <= K:
        newS.append(f(n))
        n += 1
    while newS != S:
        S = newS; T = []
        for s in S:
            M = map(lambda n: n*s , S)
            T.extend(filter(lambda n: n <= K, M))
        newS = Set(T).union(Set(S))
    return sorted(newS)
prod_hull(lambda n: factorial(n)/factorial(n//2)^2, 1024)

Crossrefs

Cf. A001013 is a sublist.

Sequence in context: A219653 A050622 A082662 * A182568 A064522 A036912

Adjacent sequences: A246660 A246661 A246662 * A246664 A246665 A246666

Keyword

nonn,easy

Author

Peter Luschny, Sep 09 2014

Status

approved