A250033 a(n) gives the denominators for A250031(n) as well as for A250032(n).

1, 2, 2, 24, 15, 45, 35, 280, 630, 2100, 2310, 27720, 10010, 140140, 150150, 480480, 255255, 2297295, 4849845, 96996900, 101846745, 106696590, 111546435, 669278610, 929553625, 966735770, 1003917915, 3123300180, 3234846615, 48522699225, 100280245065, 1604483921040, 6618496174290, 6819056664420, 7019617154550, 7220177644680

Offset: 1

Author

Stanislav Sykora, Nov 16 2014

Keywords

• nonn
• frac

Comments

See the comments in sequences A250031 and A250032.

Links

• Stanislav Sykora, Table of n, a(n) for n = 1..1000
• S. Sykora, On some number densities related to coprimes, Stan's Library, Vol.V, Nov 2014, DOI: 10.3247/SL5Math14.005

Crossrefs

Cf. A250031, A250032.

Programs

PARI

s_aux(n,p0,inp)={my(t=0/1,tt=0/1,in=inp,pp);while(1,pp=p0*prime(in);tt=n\pp;if(tt==0,break,t+=tt/pp-s_aux(n,pp,in++)));return(t)};
s(n)=1+s_aux(n,1,1);
a=vector(1000,n,denominator(s(n-1)/n))

Formula

a(n)=A250031(n)+A250032(n).