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A114800 Octuple factorial, 8-factorial, n!8, n!!!!!!!!. 13
1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 20, 33, 48, 65, 84, 105, 128, 153, 360, 627, 960, 1365, 1848, 2415, 3072, 3825, 9360, 16929, 26880, 39585, 55440, 74865, 98304, 126225, 318240, 592515, 967680, 1464645, 2106720, 2919735, 3932160, 5175225, 13366080 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Eric Weisstein's World of Mathematics, Multifactorial.

FORMULA

a(n) = 1 for n<1, else a(n) = n*a(n-8).

EXAMPLE

a(10) = 10 * a(10-8) = 10 * a(2) = 10 * 2 = 20.

a(20) = 20 * a(20-8) = 20 * a(12) = 20 * (12*a(12-8)) = 20 * 12 * a(4) = 20 * 12 * 4 = 960.

a(30) = 30 * a(30-8) = 30 * a(22) = 30 * (22*a(22-8)) = 30 * 22 * a(14) = 30 * 22 * (14*a(14-8)) = 30 * 22 * 14 * 6 = 55440.

MAPLE

A114800 := proc(n)

    option remember;

    if n < 1 then

        1;

    else

        n*procname(n-8) ;

    end if;

end proc:

seq(A114800(n), n=0..40) ; # R. J. Mathar, Jun 23 2014

MATHEMATICA

Table[Times@@Range[n, 1, -8], {n, 0, 50}] (* Harvey P. Dale, Feb 17 2018 *)

PROG

(PARI) a(n)=if(n<1, 1, n*a(n-8));

vector(50, n, n--; a(n) ) \\ G. C. Greubel, Aug 21 2019

(MAGMA) b:=func< n | n le 8 select n else n*Self(n-8) >;

[1] cat [b(n): n in [1..50]]; // G. C. Greubel, Aug 21 2019

(Sage)

def a(n):

    if (n<1): return 1

    else: return n*a(n-8)

[a(n) for n in (0..50)] # G. C. Greubel, Aug 21 2019

(GAP)

a:= function(n)

    if n<1 then return 1;

    else return n*a(n-8);

    fi;

  end;

List([0..50], n-> a(n) ); # G. C. Greubel, Aug 21 2019

CROSSREFS

Cf. A000142, A006882, A007661, A007662, A085157, A085158.

Sequence in context: A326106 A180412 A290951 * A079170 A319387 A076105

Adjacent sequences:  A114797 A114798 A114799 * A114801 A114802 A114803

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Feb 18 2006

STATUS

approved

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Last modified November 11 18:50 EST 2019. Contains 329031 sequences. (Running on oeis4.)