A062068 a(n) = d(sigma(n)), where d(k) is the number of divisors function (A000005) and sigma(k) is the sum of divisor function (A000203).

1, 2, 3, 2, 4, 6, 4, 4, 2, 6, 6, 6, 4, 8, 8, 2, 6, 4, 6, 8, 6, 9, 8, 12, 2, 8, 8, 8, 8, 12, 6, 6, 10, 8, 10, 4, 4, 12, 8, 12, 8, 12, 6, 12, 8, 12, 10, 6, 4, 4, 12, 6, 8, 16, 12, 16, 10, 12, 12, 16, 4, 12, 8, 2, 12, 15, 6, 12, 12, 15, 12, 8, 4, 8, 6, 12, 12, 16, 10, 8, 3, 12, 12, 12, 12, 12

Offset

1,2

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Example

d(sigma(5)) = d(6) = 4.

Mathematica

Table[DivisorSigma[0, DivisorSigma[1, n]], {n, 1, 80}] (* Carl Najafi, Aug 16 2011 *)

Prog

(PARI) for(n=1, 120, print(numdiv(sigma(n))))
(PARI) { for (n=1, 1000, write("b062068.txt", n, " ", numdiv(sigma(n))) ) } \\ Harry J. Smith, Jul 31 2009

Crossrefs

Cf. A000005, A000203.

Sequence in context: A291290 A006047 A285712 * A328219 A328879 A130542

Adjacent sequences: A062065 A062066 A062067 * A062069 A062070 A062071

Keyword

nonn,easy

Author

Amarnath Murthy, Jun 13 2001

Extensions

Corrected and extended by Jason Earls, Jun 16 2001

Status

approved