A114796 Cumulative product of sextuple factorial A085158.
1, 1, 2, 6, 24, 120, 720, 5040, 80640, 2177280, 87091200, 4790016000, 344881152000, 31384184832000, 7030057402368000, 2847173247959040000, 1822190878693785600000, 1703748471578689536000000
Offset: 0
Examples
a(10) = 1!6 * 2!6 * 3!6 * 4!6 * 5!6 * 6!6 * 7!6 * 8!6 * 9!6 * 10!6 = 1 * 2 * 3 * 4 * 5 * 6 * 7 * 16 * 27 * 40 = 87091200 = 2^11 * 3^5 * 5^2 * 7. Note that a(10) + 1 = 87091201 is prime, as is a(9) + 1 = 2177281.
Links
- G. C. Greubel, Table of n, a(n) for n = 0..91
- Eric Weisstein's World of Mathematics, Multifactorial.
Programs
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GAP
b:= function(n) if n<1 then return 1; else return n*b(n-6); fi; end; List([0..20], n-> Product([0..n], j-> b(j)) ); # G. C. Greubel, Aug 22 2019
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Magma
b:=func< n | n le 6 select n else n*Self(n-6) >; [1] cat [(&*[b(j): j in [1..n]]): n in [1..20]]; // G. C. Greubel, Aug 22 2019
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Maple
b:= n-> `if`(n<1, 1, n*b(n-5)); a:= n-> product(b(j), j = 0..n); seq(a(n), n = 0..20); # G. C. Greubel, Aug 22 2019
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Mathematica
b[n_]:= b[n]= If[n<1, 1, n*b[n-6]]; a[n_]:= Product[b[j], {j,0,n}]; Table[a[n], {n, 0, 20}] (* G. C. Greubel, Aug 22 2019 *)
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PARI
b(n)=if(n<1, 1, n*b(n-6)); vector(20, n, n--; prod(j=0,n, b(j)) ) \\ G. C. Greubel, Aug 22 2019
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Sage
def b(n): if (n<1): return 1 else: return n*b(n-6) [product(b(j) for j in (0..n)) for n in (0..20)] # G. C. Greubel, Aug 22 2019
Formula
a(n) = Product_{j=0..n} j!!!!!!.
a(n) = Product_{j=0..n} j!6.
a(n) = Product_{j=0..n} A085158(j).
a(n) = n!!!!!! * a(n-1) where a(0) = 1, a(1) = 1 and n >= 2.
a(n) = n*(n-6)!!!!!! * a(n-1) where a(0) = 1, a(1) = 1, a(2) = 2.
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