|
| |
|
|
A124315
|
|
a(n) = Sum_{ d divides n } sigma_0(gcd(d,n/d)), where sigma is the number of divisors function.
|
|
2
| |
|
|
1, 2, 2, 4, 2, 4, 2, 6, 4, 4, 2, 8, 2, 4, 4, 9, 2, 8, 2, 8, 4, 4, 2, 12, 4, 4, 6, 8, 2, 8, 2, 12, 4, 4, 4, 16, 2, 4, 4, 12, 2, 8, 2, 8, 8, 4, 2, 18, 4, 8, 4, 8, 2, 12, 4, 12, 4, 4, 2, 16, 2, 4, 8, 16, 4, 8, 2, 8, 4, 8, 2, 24, 2, 4, 8, 8, 4, 8, 2, 18, 9, 4, 2, 16, 4, 4, 4, 12, 2, 16, 4, 8, 4, 4, 4, 24, 2, 8
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Apparently the Mobius transform of A046951. - R. J. Mathar, Feb 07 2011
Multiplicative with a(p^e) = e+1+floor(e^2/4), e>0. - R. J. Mathar, Apr 14 2011
|
|
|
FORMULA
| a(p)=2 iff p is a prime.
|
|
|
MAPLE
| A124315 := proc(n) local a, d; a := 0 ; for d in numtheory[divisors](n) do igcd(d, n/d) ; a := a+numtheory[tau](%) ; end do: a; end proc: # R. J. Mathar, Apr 14 2011
|
|
|
MATHEMATICA
| Table[Plus @@ Map[DivisorSigma[0, GCD[ #, n/# ]] &, Divisors@n], {n, 98}]
|
|
|
CROSSREFS
| Cf. A001616, A061884, A124316.
Sequence in context: A193432 A129089 A169594 * A101113 A055155 A085191
Adjacent sequences: A124312 A124313 A124314 * A124316 A124317 A124318
|
|
|
KEYWORD
| mult,nonn
|
|
|
AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 30 2006
|
| |
|
|
