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A035265 One half of deca-factorial numbers. 5
1, 12, 264, 8448, 354816, 18450432, 1143926784, 82362728448, 6753743732736, 621344423411712, 63377131187994624, 7098238693055397888, 865985120552758542336, 114310035912964127588352 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..320

Index entries for sequences related to factorial numbers

FORMULA

2*a(n) = (10*n-8)(!^10) = Product_{j=1..n} (10*j-8).

a(n) = 2^n*A008548(n) where A008548(n) = (5*n-4)(!^5) = Product_{j=1..n} (5*j-4).

E.g.f. (-1 + (1-10*x)^(-1/5))/2.

a(n) = (Pochhammer(2/10,n)*10^n)/2.

MAPLE

seq( mul(10*j-8, j=1..n)/2, n=1..20); # G. C. Greubel, Nov 11 2019

MATHEMATICA

Table[10^n*Pochhammer[2/10, n]/2, {n, 20}] (* G. C. Greubel, Nov 11 2019 *)

PROG

(PARI) vector(20, n, prod(j=1, n, 10*j-8)/2 ) \\ G. C. Greubel, Nov 11 2019

(MAGMA) [(&*[10*j-8: j in [1..n]])/2: n in [1..20]]; // G. C. Greubel, Nov 11 2019

(Sage) [product( (10*j-8) for j in (1..n))/2 for n in (1..20)] # G. C. Greubel, Nov 11 2019

(GAP) List([1..20], n-> Product([1..n], j-> 10*j-8)/2 ); # G. C. Greubel, Nov 11 2019

CROSSREFS

Cf. A008548, A045757, A035272, A035273, A035274, A035275, A035276, A035277, A035278, A035279.

Sequence in context: A295844 A113672 A259269 * A167869 A068271 A068283

Adjacent sequences:  A035262 A035263 A035264 * A035266 A035267 A035268

KEYWORD

easy,nonn

AUTHOR

Wolfdieter Lang

STATUS

approved

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Last modified July 1 14:35 EDT 2022. Contains 354973 sequences. (Running on oeis4.)