OFFSET
0,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..10000
FORMULA
From Amiram Eldar, Aug 10 2024: (Start)
a(n) = floor(Product_{k=1..n} (1 + 1/prime(k))). (End)
MATHEMATICA
q[x_] := Apply[Times, Table[Prime[w], {w, 1, x}]]; q[0]=1; Table[Floor[DivisorSigma[1, a=q[u]]/q[u]//N], {u, 1, 300}]
seq[nmax_] := Floor[FoldList[Times, 1, 1 + 1/Prime[Range[nmax]]]]; seq[100] (* Amiram Eldar, Aug 10 2024 *)
PROG
(PARI) a(n) = floor(vecprod(apply(x -> 1 + 1/x, primes(n)))); \\ Amiram Eldar, Aug 10 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Labos Elemer, Sep 01 2003
EXTENSIONS
Offset changed to 0 and a(0) prepended by Amiram Eldar, Aug 10 2024
STATUS
approved