A067580 a(n) = Product_{i=2..n} A001222(i) * Sum_{i=2..n} 1/A001222(i).

1, 2, 5, 7, 16, 20, 64, 140, 304, 352, 1104, 1248, 2640, 5568, 22848, 25152, 77760, 84672, 260928, 542592, 1126656, 1209600, 4921344, 10174464, 21012480, 64364544, 197074944, 209018880, 639000576, 674832384, 3409993728

Offset

2,2

Links

Robert Israel, Table of n, a(n) for n = 2..2374

Example

A001222(2) = 1, A001222(3) = 1, A001222(4) = 2, so a(4) = (1*1*2)*(1+1+1/2)=5. - Robert Israel, Dec 29 2015

Maple

P:= 1: S:= 0:
for n from 2 to 100 do
  b:= numtheory:-bigomega(n);
  P:= P*b; S:= S + 1/b;
  A[n]:= P*S;
od:
seq(A[n], n=2..100); # Robert Israel, Dec 29 2015

Mathematica

Table[Product[PrimeOmega[k], {k, 2, n}] * Sum[1/PrimeOmega[k], {k, 2, n}], {n, 2, 50}] (* Vaclav Kotesovec, Dec 30 2015 *)

Crossrefs

Cf. A001222.

Sequence in context: A032045 A207035 A322440 * A325210 A181447 A082088

Adjacent sequences: A067577 A067578 A067579 * A067581 A067582 A067583

Keyword

nonn

Author

Benoit Cloitre, Jan 30 2002

Extensions

Name and offset corrected by Robert Israel, Dec 29 2015

Status

approved