A051357 Chernoff sequence A006939 divided by 2.

1, 6, 180, 37800, 87318000, 2622159540000, 1338638666765400000, 12984380089637682726000000, 2896722619368127899492763620000000, 18740906719713843949122453226304292600000000

Offset: 1

Author

Judson Neer

Keywords

• easy
• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..37

Programs

Magma

[(&*[NthPrime(k)^(n-k+1): k in [1..n]])/2: n in [1..15]]; // G. C. Greubel, Oct 14 2018

Mathematica

Table[Product[Prime[k]^(n - k + 1), {k, 1, n}]/2, {n, 1, 15}] (* G. C. Greubel, Oct 14 2018 *)

PARI

for(n=1, 15, print1(prod(k=1,n, prime(k)^(n-k+1))/2, ", ")) \\ G. C. Greubel, Oct 14 2018

Formula

a(n) = Product_{k=1..n} prime(k)^(n-k+1) / 2.