A281019 Partial products of A051953; a(1) = 1.

1, 1, 1, 2, 2, 8, 8, 32, 96, 576, 576, 4608, 4608, 36864, 258048, 2064384, 2064384, 24772608, 24772608, 297271296, 2675441664, 32105299968, 32105299968, 513684799488, 2568423997440, 35957935964160, 323621423677440, 5177942778839040, 5177942778839040

Offset: 1

Author

Jaroslav Krizek, Jan 13 2017

Keywords

• nonn

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..505

Crossrefs

Cf. A051953(n) = number of cototatives of n.

Cf. A063985.

Programs

Magma

[1] cat [&*[#[h: h in [2..k] | GCD(h,k) ne 1]: k in [2..n]]: n in [2..100]]

Mathematica

Table[If[n==1, 1, Product[i - EulerPhi[i], {i, 2, n}]], {n, 1, 29}] (* Indranil Ghosh, Mar 09 2017 *)

PARI

for (n=1, 29, print1(if(n==1, 1, prod(i=2, n, i - eulerphi(i))),", ")); \\ Indranil Ghosh, Mar 09 2017

Formula

a(1) = 1; for n>1, a(n) = Product_{i=2..n} A051953(i).