A077808 Number of prime factors of numbers containing in their decimal representation only the digits 0 and 1 (counted with multiplicity).

0, 2, 1, 4, 1, 3, 2, 6, 3, 3, 2, 5, 2, 4, 2, 8, 2, 5, 3, 5, 4, 4, 1, 7, 3, 4, 4, 6, 2, 4, 2, 10, 2, 4, 4, 7, 3, 5, 3, 7, 3, 6, 2, 6, 4, 3, 1, 9, 3, 5, 3, 6, 2, 6, 2, 8, 2, 4, 2, 6, 2, 4, 5, 12, 2, 4, 2, 6, 2, 6, 2, 9, 2, 5, 4, 7, 2, 5, 2, 9, 2, 5, 3, 8, 3, 4, 2, 8, 1, 6, 3, 5, 4, 3, 4, 11, 5, 5, 3, 7, 1, 5

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..8190

Formula

a(n) = A001222(A007088(n)).

Example

a(36) = A001222(A007088(36)) = A001222(100100) = A001222(2*2*5*5*7*11*13) = 7.

Mathematica

PrimeOmega[#]&/@(Rest[Union[Flatten[Table[FromDigits/@Tuples[ {0, 1}, n], {n, 7}]]]]) (* Harvey P. Dale, May 18 2012 *)

Crossrefs

Cf. A077807.

Sequence in context: A330328 A269427 A349391 * A021471 A088372 A331601

Adjacent sequences: A077805 A077806 A077807 * A077809 A077810 A077811

Keyword

nonn,base

Author

Reinhard Zumkeller, Nov 16 2002

Status

approved